looooooove the paint the singlet idea - am so saving that to do at mine now!!
There are some good sites around that give great ideas. Also a couple of threads along the same line.
There was a good idea that i read somewhere, that i think i want i will do as well, and that is: work out what games you are going to do, do up a little book, With a game per page, and they use each page to write answers, drawings etc. On the very last page, make it look extra pretty, and the guest use it to write their names and address's on it (for thank you cards etc) as well as like "guess what day baby born" "guess the weight" "guess the name" if these things are already known. And other things. And then the mum to be gets to keep that page as a momento! (perhaps leave room to jot down what gift they got to help with thankyou cards)
Im abit of stickler for details thou.......