The DCEmulation wiki (specifically, the Games and Demos page there:
http://dcemulation.org/?title=Games_and_Demos) is probably one of the better resources out there for somewhat older homebrew releases. Unfortunately, many of the pages there are pretty barren (or missing), but it does give you at least a start. Browsing through the first few forums over at DCEmulation (the News and Homebrew Software forums) will probably turn up a lot of information too. DCEmulation used to have a homebrew games only sub-site called DCHomebrew, but unfortunately, that's long since been lost to the sands of time... That said DCEmulation is pretty much the longest operating Dreamcast site out there, and most of the homebrew developers have hung out there over the years.
If you're looking specifically for Indie releases that have been either announced or released and pressed on disc, then Dreamcast-Scene seems to have a pretty nice list of them here:
http://www.dreamcast-scene.com/game/type/independent/ .