One of the trends of 2010 was the proliferation of StackExchange sites. I guess by now most of us visit MathOverflow along with the arXiv daily. But, there are plenty of other StackExchange sites around that may be of interest to the mathematics-community :

- Mathematics somewhat less high-brow than MathO.
- Physics still in the beta-phase (see below)
- Theoretical computer science
- TeX for TeX and LaTeX-lovers
- iPad 4 edu for those who want to use their iPad in the classroom
- etc. etc.

“Opening a StackExchange site is damn hard. First you have to find at least 60 people interested in the site. Then, when this limit is reached, a large amount of people (in the hundreds, but it really depends on the reputation of each participant) must commit and promise to create momentum for the site, adding questions and answers. When this amount is reached, the site is open and stays in closed beta for seven days. During this time, the committers have to enrich the site so that the public beta (which starts after the first seven days) gets enough hits and participants to show a self-sustained community.” (quote from ForTheScience’s StackExchange sites proliferation, this post also contains a list of StackExchange-projects in almost every corner of Life)

The site keeping you up to date with StackExchange proposals and their progress is area51. Perhaps, you want to commit to some of these proposals

- High Energy Physics
- Theoretical Physics
- Mathematica
- Math Errata Database
- Blogging and the Blogosphere
- Cryptography

or simply browse around area51 until you find the ideal community for you to belong to…