Actually, DragonRider, I've always heard that peeing after sex is better than before. During intercourse, especially missionary position, bacteria gets shoved into the urethrea. Peeing afterwards will push the bacteria out before it has a chance to travel upwards.
OP, I don't think I could really help you with this one. I've found that a slighly full bladder increases sexual pleasure. The bladder pushes into the vaginal wall making certain pleasure points more accessable. I always pee afterwards to prevent UTI as I'm prone to them. I don't think peeing before will do anything to affect your conception chances.
at 9:54 AM on Jun. 29, 2010