I would strongly recommend that, as someone who is going to want to try new things with her camera etc, she _doesn't_ get a D40, D60 or D3000, and get a D70s/D80 instead.
Why?
- built in motor so you can get and use older lenses without having to manually focus. The main example of this is the really really popular 50mm 1.8, which is about £80
second hand, and dead sharp. I've seen so many people who have bought D40's or similar with no built in motor kick themselves when they come to want this lens, and often resort to buying the £200 35mm 1.8 instead - the price difference could've got them a way better camera!
- if you ever buy / have access to a nikon speedlight flash (sb600/800/900), they can act as a wireless commander using the built in flash, for TTL capable wireless flash off camera.
- top LCD panel makes it easier to review settings, and the front aperture wheel is sooo nice to have over the strange button pressing combinations needed on the D40
- they're better built than the D40 too, so can take a few more knocks. Slightly bigger too but by no means large
- D70's are about £150-200
second hand, D80's about 320.
I'd also recommend that if possible she doesn't get the nikon 18-55 3.5-5.6, and get the 18-70 3.5-4.5 instead (this was the kit lens for the D70)... it's got a wider maximum aperture, is better built, has faster and better focussing, and more zoom at the long end. Goes for about £120 used.