A lot of import games (and games in general) are just bad, and I don't think anyone deserves to spend $60+ only to find that they've bought an overpriced frisbee. To avoid this, I think it would be a good idea for us to try and establish a list of must-play games, for all systems, new and old. Please specify what system these games are for, and if they are available in Europe (since there are a few that made it there, but not to the US).
Here are some of my suggestions:
Gameboy Advance:
Densetsu no Stafi 1-3
Slime mori mori (the prequel to Rocket Slime)
Mother 3 (The sequel to Earthbound)
kurukuru kururin (available in Europe)
the Bit Generations games (especially Orbital)
Nintendo DS:
Jump Superstars/Jump Ultimate Stars (there are only a few things removed from Superstars to Ultimate Stars, so you might as well get the newer one)
Densetsu no Stafi 4