Yep, gungrave is a great series, so give it a shot as soon as possible. And i have to agree the ending is beautiful.
How is Planetes though? i downloaded the first ep when it came out, but it didn't really interest me. Something about cleaning up space debris or something if i remember correctly.
Now that summer has started (well it started 3 weeks ago) i've been meaning to watch a few series. Heres what i had in mind, tell me if they're any good.
Gun x Sword (getting the first ep as we speak)
Hajime no Ippo
One Piece (i've seen the dubbed version, and awful VA's aside, i dont see whats the big fuss. But im willing to give it a a shot just because of the sheer popularity of it)
Full Metal Panic, original and Fumouffo (sp)