Hmm? Didn't think about that. Looking at some pics of the stereo, it looks like it should accept an aftermarket stereo nicely. Depending on the size of your budget, a double din touch screen based player with NAV would look nice. =)
This one seems to be a pretty good economy version:
http://www.crutchfield.com/App...p=144
It has a USB port along with both audio and video inputs. Looks liek they include a free rear view camera with it as well. That can come in real handy if you haul stuff or are backing up in a tight space.
Of course I speculate you are looking for something much cheaper there are plenty of single din stereos out there with aux-ins. Many of kenwood's receivers have USB ports. If you might be using an iPod, here's a good option:
http://www.crutchfield.com/App...=5684
It supports iPod control out of the box (no additional accessories. You might have to wait a bit for this one though as itdoesn't look like it's available just yet.