Billy VS Snakeman is a game which is like a parody of Naruto/Bleach/Death Note with plans to add in One piece/initial D references. Its a MMO text based RPG. I didn't think it would be very good at first, but just play it for a few days and you'll get addicted. I dunno how it happened but its really fun to play.
I won't lie, it takes a little bit of getting used to. A lot of people seem to be really put off by the tutorial day. However, most people who give it a week end up really addicted, so if you're looking for a web game, give this one a try for a few days.
Try to not be deceived by your first few days. This is a really huge game, with tons and tons of things to do. I've been playing for two months now, and I don't think I've managed to accomplish half of what you can do in the game.
In the game you can join/create villages, learn jutsus, choose bloodlines, battle in the ninja world war, rise from genin to jonin or even sannin, go on missions and even become a shinigami!
I'm really not one for text based games, but I found this game extremely addictive. Best thing is it only takes like 10 mins a day to do everything so it shouldn't interrupt anything.
If you are interested just click on my sig at the bottom and say that Ekirei referred you and you'll recieve an bonus when you've created a account. Thanks!