If you are interested in a more specific subject than just "microcontrollers" there are very good yahoo groups with lots of experts. Postings like common on this board, "PIC is great" "AVR is better" and the like are mainly absent in the good groups because they are absolutely worthless.
Groups that work well on Yahoo can be found by going here for microcontrollers:
**broken link removed**
and then look through the first 5 pages. If there are less than 100 members, the group is either new or does not work. Good groups have at least multiple postings per week, the top ones multiple postings each day to a specific subject.
Just my 2 cents, Bob