Stock ROMs, Odin Tutorials,and Callisto.ops script.It's good to have Stock ROMs .
Enigma - Android Forums
All Enigma ROMs are usually in Enigma Forum .Team Enigma usually modify Stock Samsung ROMs .Some Modifications are bizarre ,some are regular. Arkas and Perseus are Enigma ROMs
Arkas All about Samsung Galaxy 551 and more
Pretty much Stable ROMs .
Perseus All about Samsung Galaxy 551 and more
High Performer ROMs .No guarantee of stability.
WillingMagic is a sole ROM developer who is porting CyanogenMod to our Device
The Latest is CyanogenMod 7.1 which is almost perfect .
His XDA thread
[DEV][Samsung Galaxy GT-I5510 Callisto][ROM & Kernel]Unofficial Cyanogenmod 7 - xda-developers
His Mailing List