Rpg.net is one of the most important websites for roleplaying enthusiasts there is. There is several features that make it so. Number one, is the incredible array of reviews of roleplaying material. If you are interested in a new shiny book, or maybe an old one that you have never heard of, you should go to rpg.net first. They will probably have a review that tackles it.
Number two, the even more incredible forum. This has got to be one of the more awesome forums on the entire internet. I like the roleplaying general, dungeons and dragons, and open games categories. But they also have forums for LARPs, media, video games, game publishing, and lots more. These forums are filled with people that really know RPG’s. If you step back a bit, you can really get the pulse of the hobby; what games people are playing, how people are playing certain games, what new stuff is turning heads, or whatever. Plus there is Tangency.
Number three, is the very interesting columns that are archived there. They are very informative. One of my favorites is a long series on being a game retailer. Maybe someday.
Overall, I think that boardgamegeek’s RPG section will eventually replace the aging rpg.net. But for now, it is the premier site for people that play and thing about role playing games. I suggest you check it out.