In addition to (and prior to) Stack Overflow, there are quite a few special-purpose mailing lists and forums out there for programmers.
In my case, there's the Tomcat mailing list (i.e. [email protected]), the mysql mailing list (i.e. [email protected]) and the many forums at java.sun.com. Then there are those used for more hardware-specific tasks (like ones for the NSLU2, etc.).
THe benefit of these lists is that questions are specific to the platform (i.e. Tomcat, MySql, the NSLU2, etc.) and also tend to have a great collection of experts and developers.
What are some of the ones you subscribe to and/or use most frequently, aside from Stack Overflow?
-Richard