Transmission leaked after flushing, and needed to be serviced thereafter. Not the fault of the car.
Suspension (shocks & struts) replaced at 75,000 miles.
Door locks all failed (automatic type) at 65,000 miles.
Replaced battery with optional heavy-duty sized battery after investigation revealed a couple of dead cells. This upgrade is a must in colder climates, but make sure that the new battery will fit under the hood -- some are too tall.
Intermittent electrical problem in dash -- lights all go out. Unresolved, but hasn't happened in a long time (since the battery was replaced - and that may have been the cause.)
Starter motor failed at 70,000 miles.
This car seems to chew through tires regularly (one set each 20,000 miles or so for the last 4+ years), but the suspension replacement has seemed to help out a lot, and I recently put a better quality tire on it -- Goodyear Regatta 2, with an 80,000 mile guarantee). My shop recommended getting the tires rotated with every other oil change and checking the alignment twice each year to see if we can eliminate this problem in the future.
Other items replaced or serviced include motor and transmission mounts, spark plugs, serpentine belt, brake shoes, and regular routine consumables.
None of the items that I have listed makes this a bad car. The car is great for a family with two small kids (and lots of their friends). It holds a great deal of people and luggage, is comfortable, and gets decent mileage -- better than any SUV. I would - and probably will - buy another one. In my extended family, there are now 4 Caravans, and they have all provided good service. Definitely shop for the six-cylinder version if buying used, however -- not the four! If I were looking today, I would consider a higher trim package with the trip computer and compass, etc.