Cyanogenmod, the most popular custom ROM on Android
As far as wide-spread adoption is concerned there is no custom rom that has a user base comparable to Cyanogenmod. Over the last 4 months Team douche has been cranking out code and release candidates trying to perfect this rom removing bugs and adding features the whole way. A lot of the tremendous work taken up by thousands of developers the world over has been getting features and code from the froyo based Cyanogenmod6 into Gingerbread based Cyanogenmod7. According to Cyanogen in his blog post: "CM7 is based on the 2.3.3 (Gingerbread) release of Android from Google. We've added most of the great features from CM6 you know and love, and many new ones including support for several tablets. We are currently providing support for 30 devices! I continue to be amazed with this community and the dedication of everyone involved."
Cyanogen does it again
I second that motion. The people responsible for the work that is Cyanogenmod7 deserve kudos and it's a darn near perfect work (it's my daily use rom on Supersonic). CM7 comes highly recommended so if you're looking for a dose of Gingerbread and your phone is supported flash this. You wont be sorry. You can get the Cyanogen mod 7 release here and you can grab the cm7 gapps package(Google's apps) from here. Don't forget to make a nandroid back up and secure your investment. Looks like Cyanogen and the gang have done it again.