Chishola1, the slickest setup I've seen is simply to upgrade a factory AM (or whatever radio your car came with!) to more modern internals. There are tons of local shops that can do this. After it's done, your actual stock radio, which looks like a boring AM-jammer, can actually play AM, FM, Bluetooth, or, if you hook up the connectors, even MP3s off a thumb drive. Something like 45W per channel, too, with pre-amp outs as well. To change modes, you click the volume knob to 'off' and snap it right back on. So, *click-click* you're in FM. *click-click* you're now in Bluetooth. *click click* you're in MP3 mode. Etc.
The coolest thing is, everything works exactly the way it did when it was original. All of the settings for fader, balance, and even switching tracks can be handled with the original knobs, and no external modifications. All of it's pretty easy once you see how to do it. If you didn't tell someone about the upgrades, aside from it playing in stereo and having more volume, they'd probably never know you did anything.
The only drawback is cost, as the upgrade is about $600 or so, not including new speakers. Just google Aurora Designs and find someone near you that can do the upgrade, as they only sell to authorized dealers. Even at that cost, you're still comparable to any modern head unit with the same features, and even then you wouldn't have one that looked stock. Sound quality on the Aurora Designs upgraded units is phenomenal. Much better than their 'new' competitor units.
I know you don't have a factory radio, but you can usually find a cosmetically sound one that doesn't work for pretty cheap!