Not many things at all.
New Radiator at 64k.
New Windshield at 12k (Dealer replaced it before I purchased it)
New Windshield at 50k.
The Infamous dash spasms.
I am very pleased with my Jeep. I got it used in 2001 from my Local Chrysler Dealer with 12k miles on it, I believe it was a lease return.
The gas mileage could be better, but it's a Jeep.
It now is 7 years old with 69k miles on it and still has the original serpentine belt, battery and has never had a tune-up performed, but I change the oil every 3k miles or when I get bored... whichever comes first.
I got 60k mile tires for it and they've only lasted 15k, and I don't drive like Richard Petty.
I am astonished at how well it does off-highway, I've had it in water up over the front fenders and not get stuck, but due to poor tires I did manage to bury it in mud up over the tires and this is a stock Jeep. It is also very good in the snow as well.
If you've heard the rumors about the old CJ's and First Generation Wranglers being noisy and having poor heat you'll be surprised to see that the new generation has been changed A lot. The Heater is unbelievable and the soft-top is not as loud as the older Wranglers. The only bad thing about the soft top is that after a while the window zippers freeze up and leave the track which is an easy hour fix.
I love having the roof down, when I first got it, it took me 2 hours to get the roof on or off, but now I can do it in just under 5 minutes on a bad day. Once I had to do an hour and a half of Interstate Driving with the top down in the rain, but thankfully they were smart enough to put drain plugs in and easily removable carpets.
Overall it's dependable, cheap and I will own it until I literaly run it into the ground and when that happens I'll be getting another one.
The first generation Wranglers (YJ) actually had excellent heaters.