Before anyone else has a chance, do a search. This has been discussed a couple of times.

That being said, watch the mileage. The timing belt is probably the single biggest item to watch. It's "supposed" to be changed at 105k. Some do, some don't. If it is close or over this, check to see if it has been changed yet. If it hasn't, it's an expensive thing to have done ($800-1000). If it hasn't and the belt snaps, major engine damage is likely (not guaranteed, but very likely). This will generally include the water pump, thermostat, pulleys, etc. with it.

Another thing to watch for is a cracked exhaust manifold (3.3L, V6, right side). This isn't a BIG issue, but it's not that uncommon.

Other than these, look for overal condition. What year are you looking for specifically?

You may also try to find out what "mods" have been done. Some are more useful than others and more reliable than others too.

HTH!

-G