http://www.chapelhillrent.com/
I'm from the area originally, so I did some apartment hunting while I was visiting my parents for the holidays. I actually put a deposit down on an apartment on MLK/Airport Rd, which is on multiple bus lines that go directly to campus... parking around campus is pretty much impossible.
Here's a more specific listing of places directly on a bus route:
http://www.ci.chapel-hill.nc.us/index.aspx?page=705
And more details about the bus routes:
http://www.ci.chapel-hill.nc.us/index.aspx?page=1176
There are also some rental houses behind Franklin and Rosemary Streets that would be within walking distance, but maybe a bit noisy because that area to attract a lot of undergrads. Of course, being able to walk home from Franklin Street on weekend nights would be fun (because we'll be going out all the time, right???). The neighborhoods on the other side of Manning Drive off Mason Farm Road seem nice and more grad student-y, but I haven't really explored that area very much.
Make sure to ask about any UNC grad student/employee promotions because I was able to get some fees waived and half off the first months' rent!
Congrats on the acceptances