Well from here are a few tidbits ClubPenguin.com says about that:

Dress up your penguin!
* Buy clothing and accessories
* Give your penguin a new style each month
* Come up with thousands of unique clothing combinations
* Unlock more actions with different clothing combinations

Adopt more puffles!
* Adopt more than one puffle
* Get all the colors of puffles
* Buy furniture for your puffles

Get more out of Club Penguin!
* Members see more room available on each server than a non-member sees, which means less waiting time
* Open your igloo on the map and meet more friends
* Be the first to discover new areas
* Get creative

We also wanna point out these great facts:

Club Penguin has been accredited as meeting BBBOnLine standards. Children’s safety is of utmost importance to us. Memberships allow us to maintain high levels of safety. A safe chatting environment is more fun!

Club Penguin also gives a portion of all membership proceeds to charities worldwide.

Club Penguin has the pleasure of experience staggering success with over 700,000 current paying members. The website is updated every week and keeps growing in efforts to ensure that the site is as safe as it can be.

Memberships to the site are reasonably priced offering a monthly subscription for 5.95, a 6 month subscription for 29.95 or a year subscription for 57.95. Although some parents may feel this is a high fee to pay for a site for your child to use. You truly can not put a price on safety when it comes to the internet. Club Penguin is fully supported by the paid subscriptions to their site, there is no advertising or marketing of any type. Keeping a site free of advertising and marketing also keeps your children from seeing ads that are not targeted for their eyes.

While Club Penguin is open to children of any ages the site is more geared for children between the ages of 6 and 14. They offer games, education and interaction with other children. As the year progress Club Penguin will be offering even more new games, new features, new adventures, new missions and a lot more.

Clubpenguin.com is a virtual world, for internet chatting, designed specifically for kids. Of course, New Horizon Interactive kept kids’ safety in mind throughout the process of creating the site, and stayed away from blunt marketing appearing to kids.

Creators say on the site they consulted parents, law enforcement representatives and educators, as well as completed research on online safety before releasing clubpenguin.com to the public in October 2005.

Since clubpenguin.com’s introduction, it has become the number one game on Miniclip. Club Penguin is partnered with BBB Online, as well as NetSmartz, which is a partnership of both the National Center for Missing and Exploited Children and the Boys & Girls Clubs of America.

Club Penguin has also received the 2006 Editor’s Choice award from Children’s Technology Review Magazine.

The world of Club Penguin is updated weekly, and 80% of staff consists of moderators and safety personnel (many are parents, too). Clubpenguin.com is not funded by advertising revenue – it is funded entirely by subscriptions. Subscriptions are $5.95 a month.

Buying a membership allows a kid to dress up their penguin in different outfits, decorate their igloo, host parties in their igloo, and adopt pets called “puffles”.

As part of the site’s commitment to kids’ safety, posting personal information is discouraged. Club Penguin conforms to the Canadian Code of Practice and the U.S. Department of Commerce’s Safe Harbor Principles.

The LED light on the spy phone spells out “you are cool” in Morse code. You can learn this by going to the phone in the F.I.S.H. Click the antennae and it will pop up a secret coded message.

Finding Rockhopper is something just about every penguin out there wants to do (If they haven’t found him already). You can talk to him and you can get a free background!

For one thing, Rockhopper is Club Penguin’s account, he can be a bot or a real person (depending on the time of day). So that means he can be on any server, in any place he wants to be. However, sometimes he likes to go on these servers a lot (that doesn’t mean you can’t find him in other servers): Mammoth, Frozen, Mittens, Rocky Road, and any highly populated Servers (the ones on the left column of the first page of the U.S. servers list, for example). But nowadays, he can be on any server!
Now, finding him is kinda tough, but it can be done. Two helpful factors are: that he’s slightly larger than the average penguin (he’s bigger, thus easier to spot if you’re in the same room as him). And there’s always a flood of penguins around him (they’re usually all red). And one surefire way of knowing he’s in a room is that you can’t get into the room because its full and there’s hundreds of penguins clobbering to get into the room. Also, he moves around the rooms in Club Penguin every so often if he’s on the Server. For example, he might appear in the Ship Hold, then move to the Beach, then the Town, then the Iceberg, etc. But sometimes he stays for a very short (or long) time in one or two rooms and switches servers.

And he’s most likely to be in the Dock, the Beach, the Iceberg, the Pizza Parlor, the Plaza, and (this is the one he’s most on) his ship, The Migrator (RH’s ship sank. Scratch that). Basically, rooms that have a large penguin capacity, unlike the Mountain Top which can only hold around 20+ penguins before its full.
As for times he’s on, he’s most usually on during peak hours (times when everyone’s on), or he can also be on during random times of the day and night when there’s a moderate amount of people or no people at all.

Methods of finding him
First, you gotta check if he’s online or not. Type in his username in the log in screen and type in a random password (at least five digits long). It will say he’s banned if he’s offline. It will say ‘Incorrect password’ if he’s online. If he’s offline, stop and try again later. Here is a pretty good method: Once you find out he’s on, Get onto my Bribble chatbox. Sometimes the people on there will help you. Check the servers I mentioned above. Then check servers that have more dots than they usually have. For example, you see Snow Globe or Tundra has 1 or 2 more dots than the servers around them. GO THERE! And for every server, check the places I mentioned (Beach, Dock, etc.). I suggest staying at a crowded place for a bit if someone might shout where Rockhopper is.
I also suggest using Miniclip.com’s Club Penguin because you don’t get taken to the home page everytime you log off. Also, RH used to give the eye patch, but now, he only gives the free background.
Here is the method I use the most: I do the same thing as above, but I don’t go onto my chatbox. Instead, I rapidly skim through all the major servers I mentioned earlier, then any unusually populated servers, then servers with names relating to Rockhopper or a mission (Rocky Road, Polar Bear…), then servers at the top or bottom of the page. I usually find him by the time I search unusually populated servers. Sometimes, a person shouts out where he is. I skim through all the places I mentioned, especially the Dock and Beach. I’ve actually found him a lot of times on Tundra server.
One very tedious and dull way to find him is to check if he’s on, and then check all the servers I mentioned in all the places I mentioned. Then start checking servers with three dots or more (it doesn’t have to be only U.S. Servers, check all nations). And if you still don’t find him check all the other servers with two or less dots and the places on those. And if you still don’t find him, He probably logged off or changed servers/rooms while you were checking. And on top of that, this might not work because he can change servers any time he wants to (but he usually changes every 10-25 minutes so don’t worry).
A somewhat effective way is to check servers that are not usually filled up but are oddly full or close to full for some reason, and go look on there. I’ve actually gotten this to work before.
Another way is going on the most popular servers in the most popular places and just wait for news of him. It could take a few minutes or a few hours (ugh, you should try another method if it takes that long), but someone just might shout “RH is on Mittens!” or “He’s on Mammoth!” or “Rockhopper’s on Tundra! WOOT!”. If they do, FIRST check to make sure Rockhopper’s not on the server you’re are right now. If you are, don’t log out, they’re probably trying to trick you, Rockhopper might just be in that server on the Ship Hold. Try double checking to make sure he’s not in any of the rooms on that Server, then rush on to that server before it fills up and rush to the ship hold (he’s most likely here) before that fills up as well. This has worked a few times for me. And sometimes he appears first on the Iceberg so check there.

Once you find him, its awesome! There’s about two dozen penguins there asking him questions and HE ANSWERS THEM (with a pirate accent). Also, you get a free Rockhopper autographed background if you try buddying him (You can’t buddy him….but you can put him on your ignore list if you want), you can go to his “home” (The Migrator is his home.DON’T CLICK FOR HIS SHIP. Since the Migrator sunk, you won’t go there, you will just lose connection), and you can send him postcards and I hear he sometimes sends one back! And you can follow him around when he walks around Club Penguin.