E.F.
I was a balloon from about 28 weeks on too! Frankly, I never really found anything that worked for me, but you can make sure you are cutting out nearly all salt (including hidden sodium in foods-- read your labels!), drinking tons (8-10 glasses a day) of water and/or non-caffenated beverages, and doing the legs-up-the-wall thing a couple times a day for no more than 5-7 minutes at a time. Also, staying off your feet/ out of the car as much as possible (hard with 2 at home, I know.)
If there is an upside to it, it's that you lose a TON of weight the week after the baby comes, lol!