I've been looking through my collection of games to see if there are any games that might come in handy for S&S sessions.
Obviously, for exploration and mission generation there is Star Explorer (http://boardgamegeek.com/boardgame/6735/star-explorer). Which reminds me, really must order a new copy to replace my (rather battered) original.
If you want to run larger-scale firefights and tactical scenarios, then there is Star Fleet Marines (http://boardgamegeek.com/boardgame/124404/star-fleet-marines-module-1-assault). All you need to do is file the serial numbers off, and there you go!
While I have a fair number of starship combat games in the family, I don't think I'd move away from the system in the S&S rules. It's less complex than a lot of other games. However, the SFB SSDs and STIII recognition manuals do give some ideas for statting up new vessels.
Any other thoughts from people?