The easiest homebrew solution yet
Well, we no longer think it could get any easier. The newest device to come out of haX0r-land, the sillily named DS-Xtreme, is nothing more than a DS cartridge. It works as a simple mass-storage device ... simply move the applications or files to the cartridge using a USB connection, and poof, instant homebrew. It comes with a built in MP3-playback app, and it has two bitchin' LEDs for good measure (check out the embedded videos after the jump). The downside? It only contains 512 MB of memory, and it can't run anything built for the Game Boy Advance. Still, for the fence-sitters out there, this might be enough to push you over the edge. Check it out.
[Sillily is so a word.]