Got a question? There are many newsgroups and forum sites specific for vendors of MCUs or vendors of Development Tools

In future this site will provide a list of the most popular forums in the 32-bit world. Feel free to request adding a link to your specific forum.

For all microcontrollers and embedded related topics, this Google group, comp.arch.embedded can be used.

There are several forums. related to the general ARM architecture but I have yet to find one, that is really active. Much more active participation is in the vendor specific forums, such as a forum for AVR, SAM7xx, LPC2000, and so on.

For now let's list some really popular ones dedicated to particular architectures 

• For STM32 lots of sample programs and an active community uses the Primer and Primer2 from Raisonance
• For Atmel SAM7, SAM9 and soon SAM3 based microcontrollers  
• For Philips / NXP LPC2000, LPC3000 and soon LPC1000 based microcontrollers
• For Renesas all of their H8, H8SX and SH32 based MCUs

Now a list of popular groups related to Development Tools

• Keil offers an active and very productive forum
• Raisonance runs the STM32circle community
• Micrium, the company that created and maintains uC-OSII has a Yahoo forum as well