I don't get extra thristy when I'm pregnant, but when I'm nursing I get INSANELY thristy! My husband knew to bring me a huge glass of water each time I nursed. Somehow having ice cubes in water always helps me, the colder the water, the more it seems to quench my thrist. Sometimes also if I'd had so much water already it was coming out my ears, I would have a lemony hard candy instead, and that would take care of the thrist for a while. Another thing that often tastes really good to me instead of water is grapefruit juice, and it's fairly low cal too. I've never nursed and been pregnant at the same time---but I bet that could multiply the thrist! Good luck!
Suzanne (37) and DH Tony (41) + William (9, severe PE, born at 32 weeks) and Freddy (6, fairly typical pregnancy) and Baby (due approx. 8/26/04!)