Currently I'm thinking Renegade Legion and TORG, but don't remember if they were part of the same game universe or not.
Always enjoyed the TSR Star Frontiers' RPG - Knight Hawks space combat system.
And yeah, Starfire.
Of course, all of these games are totally out of print, with the exception of SFB.
I thought I read somewhere about a space boardgame based on the Honor Harrington universe, as Weber of course co-writes with Steve White, who originated Starfire and has written books based on Starfire. Have seen absolutely nothing about that though, so it might have been just a rumor.
Wasn't there a 40K space combat game? Battleship Gothic or something? [Not Space Hulk.]