Because, there is no other accurate or concise thread on the internet; I'll make one.

Many cut-rate and 2nd tier motherboard manufacturers have been omitting the ECC feature from most AM2 and AM3 boards for quite some time.

Also note, this is about Unbuffered ECC (72-bit) DDR2/3 DRAM support.
(* Means there is support mentioned in a manual or docs)
(* Means there is unverified\unofficial support)

List for AMD 890FX Motherboards:

ASUS (All models)
Biostar TA890FXE *

List for AMD 770 Motherboards:

ASUS (All models)
Gigabyte GA-MA770T-US3 *

Please list other boards that support ECC, in this thread Thanks!