Bebop and Samurai Champloo would be pretty neat in a live-action version, but I think it kind of betrays the whole feeling of the anime. Sure, it would look nice, and assuming there was a good storyline behind it, be pretty kickass, but part of the reason to watch anime is the differences and similarities to reality.
Also, they've claimed to be working on a live-action DBZ since I cared about that show. What's that, 5, maybe 6 years now? I doubt that's happening.