Going from Canon Rebel T1i to a Nikon?

I'm seriously looking at saving for a new camera, and I'm wanting a Nikon.

What is an inexpensive, good Nikon DSLR on the market right now?
I'm just doing my research before I set in stone which one I want. I've looked at the D90, but I was just wondering if there's something else that is less expensive, but still takes good pictures.

Added (1). Thanks for all the great answers so far…
It's not that I don't want my Canon anymore, I would just like to have a Nikon as well!
And I don't have very many accessories at all for my Canon, so i don't think I'd be losing any money right there.

The D3100 is exactly what you're looking for, it has great image quality for such a cheap camera (or just any camera in general), and it's cheaper and newer than the D90

All manufacturers make high and low end cameras. Read model specific reviews especially the 1 or 2 star complaints.

Any of the Nikon DSLRs will be able to take good pictures so you can pick anyone within your budget. However before switching have you consider upgrading. If you already have canon accessories like (e.g external flash) you could save some money by buying a higher end Canon body. You can still use your existing lens.

Of course, if you currently only have the Canon body and 1 lens, then you will not save very much if you stay with your current system.

I'd get the D5000, it has great things and features. Why don't you want your T1i anymore?