The New Play Control versions are coming out in the US. There's already been a couple of releases, Pikmin and Mario Power Tennis.

If you are looking to modding/using the Homebrew Channel, I highly recommend picking up Tatsunoko vs. Capcom. It's a very fun fighting game in the vein of the Marvel Vs Capcom games, but will probably never come out in the US because of all the licensing issues that would be involved with the anime characters.

And I haven't used the Homebrew Channel myself, but most ROM files, especially for 8-bit era games, are very tiny. You could probably get 100+ (at least) NES/SMS games on a 256MB SD card. But really, you should just get a bigger SD card. They're getting dirt cheap nowadays. You can pick up a 2GB one for $5-10.