Things that you need but don't cost too much.
Nail clippers, lots of bibs (mine were chucky), breast pads (even if you don't BF you'll still leak till your milk dries up), maternity pads and panty liners, singlets and socks.

My SIL is 6 weeks PG and we were at MIL's at the weekend and she dragged out a huge bag of stuff she's been buying since she was 18, she is 28 now. She can't walk past the baby sections at sale time and she has heaps of clothes. It's never too early to start a "glory box" just don't go too nuts!