Here are a few pictures of my mobile radio installation in my Honda Element. The radio is a Kenwood TM-D710A, with a Greenlight Labs GPS unit.
This shows the overall location of the radio control head and speaker. The actual radio is mounted under the driver's seat but is your standard black box with wires coming out. Nothing too exciting there. The leads to the speaker and the control head go back up through the dash and out through a dremeled hole in the subwoofer enclosure (mesh area beneath the control head), which you can barely see at the top right corner of the control head. If I ever sell, the entire enclosure is a <50$ part that is simple to replace and is the only visible "damage" for the entire installation.
Close up of the control head.
Diamond NR73BNMO dual band antenna mounted on the the Diamond K412SNMO "trunk lip" mount mounted on the hood. The coax runs through the fender well to the front of the car, where it's joined through cable harness with the battery leads, back through the firewall, and under the dashboard. There's an existing hole in the firewall to the driver's side fender, so no drilling was needed.