A price range would be helpful. I wouldn't bother with the Pentax K2000, but the K200D seems to be very nice indeed with it's weatherproofing and all. Then there's always the D60, which I find to be surprisingly comfortable to hold. And don't forget about Olympus, personally I'm not crazy about them, but I've gotta admit that they've got good pricing.
The step up from those cameras would be either the new Canon T1i or the Nikon D5000 (personally I'm leaning toward getting the D5000 myself.)
And I can't help but mention the Nikon D90... it's what I'd really like to get, and I'm currently trying to decide if it's worth the extra money over the D5000.
So, those are the cameras I've personally been interested in, I'd really need to know more about what you like in a camera to be of much more help. Oh, and I'd highly recommend
this website in your searching.