Oh, I change my vote from Arena FMV. Instead, I want the entire Automation Features thread added
In-game MP3 support (with 2 playlists, one for combat, and one for the strategic map) would be a close second. Initially we'd make the playlists of MP3's laying around, but it would be awesome if by patch 1.5 there was a full set of combat themes, one for each race, like in Star Control II. Pre-patch, I'd probably use the Ur-Quan theme for Ryleh, Orz for Atlantis, Yehat for Tien Chi, Syreen for independant Amazons, Illwrath for Machaka, Druuge for Abysia, Supox for Pangea, Utwig for Ulm, Thraddash for Marginon... hmmm, some of them don't fit too well. But that's OK, there are plenty of other games to draw from.
-Cherry