The only reason to have color would be to show videos, but I don't see why you would want video. It would just fill up your hd to watch little tiny videos.
unless of course there was some service similar to iTunes Music Store that you could download movies optimized for your iPod. That would be some big files.
Direct downloads would be cool, though, and maybe bluetooth, so you could connect to the store through your phone. That would be some slow downloads, though, wouldn't it? Better slow than not at all, I guess.