Thri-Kreen is one that pops into my head.QUOTE]
Gotta agree on the Thri-Kreen. A long time ago there was a really cool game made by Electronic Arts called Starflight and Starflight 2 (a lot like Star Control 2). Anyway, one of the races of aliens you could crew the ship with were the Velox which were human sized insects. There were also the Elowan which were plant people and the Thrynn which were lizard folk (looked more like Firenewts than Lizard Men). The Thrynn had a natural aptitude to being Comm Officers and were fairly tough while the Elowan made great Doctors and Comm Officers but were very frail. Velox made great Engineers and Navigators and were fairly tough too. Humans were decent at everything but not excelling in any one area.
Hmmm... may have to dig out Traveller T20 and base it on Starflight.