Full Metal Alchemist
Outlaw Star
Rurouni Kenshin
Gundam Wing
I'm not as big an anime head as some guys, but these are the ones I've seen that I'd like to see done.
Full Metal Alchemist:
A lot of stuff would be left out of the first movie, but the Elric brothers, their first encounter with the Hummoculus, a State Alchemist plot with Roy Mustang and a satisfying resolution involving the temporary creation of a philosopher's stone... it could be fun, but It wouldn't be a summer blockbuster... a good adolescent's movie, like Eragon or Dark is Rising or something... except, y'know, good.
Outlaw Star:
I just like it a whole lot. I think the characters are a LOT of fun, and it opens up for some very fun action... kind of like an amped up 'Serenity.' In fact, that's exactly what it would be like, an amped up serenity, just with different character balances.
Kenshin:
Didn't get to see a whole lot of this, but I would love this.
Gundam Wing:
Seriously... this almost writes itself. It's almost conceivable that this could happen (almost) and, on top of that, it's got some of the most intense action conceivable. I'm the previous Gundams were great (or else why would GW have ever been made), but I think a space-battle is almost unavoidable. I actually wouldn't object to a brand new Gundam cast/era, espeically if it fit into existing continuity.
The more I think about Voltron, the more contrived it feels. I love the cartoon, and would love a movie, but I can't really see Voltron happening... unless it was, like, a long time ago in a galaxy far, far away.
And while Wolf Rain was a great cartoon experience, the fact is that a lot of that wolf action is going to be all-CGI, making it kinda of a cartoon any way you slice it. The human elements are pretty limited, even though they are present.