I have an "old" Samsung 191T 19" hooked up to my MBP. It has a 1280x1024 resolution -- I wish it was higher, but like I said, it's "old".
DVI is a must, IMO. I wouldn't buy an LCD without it.
The 1680x1050 20" Samsung mentioned above sounds like it might be a good choice. I might get one for myself.