I found it after I started using my first flashcard a bit, around 3 years ago I bought an R4, and I believe that at the time there were only a few cards better, and later I bought a DSTT, both were quite satisfying for my needs, and eventually I bought an AK2.1 just for the hell of it. The first site I started using was ndshb.com, and I found GBAtemp by searching homebrew on google I think, or there was a link there, but it wasn't until some time later I actually registered.
tl;dr version I found gbatemp by searching google for homebrew