I realize that I’m late to the party on this, but there is a new mathematical website precisely for answering questions: Math Overflow.   Modeled on the Stack Overflow site for programmers, Math Overflow seems to have done a nice job in attracting a large crowd of professional mathematicians and students.  Questions tend to be answered quickly, and there is an interesting “reputation” feature that measures one’s respect in the community.  This is probably a much better approach than tossing out blegs (for readers here that are bloggers) since many more people will read it, and since the questions will be available in a common source for other mathematicians.  Since there are other sites that have active communities for math help, Math Overflow restricts itself to questions that are “of interest to at least one mathematician.”  

Anyway, it’s still not at all clear where Math Overflow’s niche will ultimately be, but the community seems to have generated substantial discussion on algebraic geometry and category theory.   In the future, perhaps it will make reading papers a much less difficult experience–in fact one of the questions I asked came from something that I didn’t understand on the arXiv.

Another site, which is almost a year old now, is nLab.  This apparently started out as a spinoff of John Baez’s blog but now may be more like the Bourbaki 2.0 project I suggested.   One of the pleasant features of nLab is that it is a wiki, and there are a wide variety of relatively elementary topics that still aren’t covered.   Some users seem to edit the website to post course-like notes or simply to refresh themselves on some topic.   I myself will probably cross-post some of my more textbook-ish entries (in a modified form) there.   Finally, based on comments of Urs Schreiber and Todd Trimble, I should also point out that there is a nForum to log one’s changes that makes it easier for other users to track changes.   This website also looks like fun, and I recommend actively participating.

Math Overflow and nLab have entirely different cultures, so it seems they will be able to coexist mostly peacefully.   However, both sites seem to be dominated by algebra and category theory, even though this is not the intention.   Maybe this is because algebra lends itself better to a wiki, but I don’t know why this is the case for Math Overflow.  Anyway, as more people hear about it, all areas of mathematics should eventually be covered. 

Spreading the word is what this post is for.