Timing belt and water pump, $1200-1400, specified for replacement every 90K miles or 6 years, whichever comes first, on a '91-96, 105K miles or 7 years on a '97-03.
All other scheduled maintenance - see the FAQ (Maintenance - Schedule).
Cooling system hoses.
If you haven't seen it yet, check out the Used Car Checklist in the FAQ (Buy, Sell, Ship, Store - Used Car Checklist).