Hadimec AG - for board level assembly
Meng Engineering - for FPGA VHDL designs
68HC11, 68HC12, 68HCS12 using GNU compiler - good group
68HC12 processor - good group - alternatively try Freescale's own forums
LPC2000 processor (including LPC210x, which we love) - very active group with active participation from Philips experts!
Atmel AT91SAM7 family - SAM7 reference - or ATMEL's own forum
ST Microelectronics for discussions about the STR91XF (and others)
Embedded processors PIC, AVR, HC11, HC12 and some more - general forum mix
Apprentice workshop - Bern