Webpages for specialized communities First, my apology for this soft question. My excuse was that I really think this may be of interest to the community. I would understand if it gets closed (I have advocated closing some soft questions myself, so it's fair).  
Background/Motivation: Recently at an AMS meeting I decided to attend a special session outside my interests and had a lot of fun. Also, to learn about what is going on in a different but related area, I found it  very useful to look at some recent conferences and start by  skimming the list of speakers and abstracts/notes. So a website with recent and upcoming conferences would be useful. They are not always easy to find with Google. 
Requirements: Since this is soft, let's take some care to make sure it will not be too easy to answer. So let's define "specialized community" to be "there is at least one AMS special session devoted to (part of) it. Also, the more useful the website is the better (for example, one should preferably contains list of conferences, and perhaps more) 
Examples: here is one I visit frequently: for commutative algebra 
Another one I found recently and like a lot: Finite dimensional algebras

Surely there must be others? 

 A: There is also the Number Theory Web.
A: Kiran Kedlaya maintains a list of upcoming conferences in arithmetic geometry: http://scripts.mit.edu/~kedlaya/wiki/index.php?title=Conferences_in_Arithmetic_Geometry
Ravi Vakil has a list of upcoming conferences in algebraic geometry:
http://math.stanford.edu/~vakil/conferences.html
A: Dispersive wiki: http://wiki.math.toronto.edu/DispersiveWiki/index.php/Main_Page
Complexity zoo (if computer science counts): http://qwiki.stanford.edu/index.php/Complexity_Zoo
Deep Inference (from structural proof theory): http://alessio.guglielmi.name/res/cos/
n-lab (category theory): http://ncatlab.org/nlab/show/HomePage
A: Here comes some sites that list upcoming (and also previous) conferences in 
the field of operator algebras
One maintained by Paulo Pinto: http://www.math.ist.utl.pt/~ppinto/conf2004.html
Another maintained by Michael Anshelevich: http://www.math.tamu.edu/~manshel/meet.html
And a third maintained by Narutaka Ozawa: http://www.ms.u-tokyo.ac.jp/~narutaka/schedule.html
Operator algebra page of N. C. Phillips: http://darkwing.uoregon.edu/~ncp/OpAlgResources/OpAlgPages/opalg.html
A: Not sure if these have special sessions, but they are pretty broad:


*

*K-theory

*category theory
A: Jon McCammond's geometric group theory page.
A: Compressed Sensing
A: Galois Theory Web Page
Valuation Theory Home Page
A: Foundations of mathematics: http://cs.nyu.edu/pipermail/fom/
A: As far as logic goes, there is the Association of Symbolic Logic website.  It has a very comprehensive list of logic meetings, which includes the ASL meetings, the officially sponsored meetings, and more.
A: Sarah Whitehouse keeps a list of meetings in algebraic topology and related areas.
A: A few more for Logic:
Mathematical Logic Around the World contains a lot of useful information about Logic departments, Logic journals, LaTeX for Logicians etc. The events section is a little outdated though.
The European Set Theory Society has conference announcements as well as slides from the conferences.
There is also the Young Set Theory Network, which has conference announcements, and hopefully will have more things in the future.
A: Open source mathematics software -- we've had a lot of talks about Sage in special sessions, and next year in Boston we'll have an AMS minicourse on Sage. 
A: Motivic or $A^1$-homotopy theory.
Affine algebraic geometry.
Cluster Algebra Portal.
