Basically everything 
Seriously, though, what you will need to repair depends on what you have repaired already and when you did it.
Timing belt / water pump / thermostat - every 75K miles
How's your clutch? That's going to go someday, if it hasn't yet
.
Suspension - control arms, shocks are all possible failure points
PCV system for certain, if you haven't cleaned / replaced clogged parts on a regular schedule, probably your valve cover gasket as well
Engine mounts - they fail every 60k or so, make sure you replace them or you might be looking at a flex pipe replacement.
Very expensive things: Catalytic converters (parts cost), heater core (labor cost). Let's hope these don't go bad. Not much you can do about the cat, but make sure you flush and change your coolant regularly and use only VW approved coolant.
Seriously, though, what you will need to repair depends on what you have repaired already and when you did it.
Timing belt / water pump / thermostat - every 75K miles
How's your clutch? That's going to go someday, if it hasn't yet
.
Suspension - control arms, shocks are all possible failure points
PCV system for certain, if you haven't cleaned / replaced clogged parts on a regular schedule, probably your valve cover gasket as well
Engine mounts - they fail every 60k or so, make sure you replace them or you might be looking at a flex pipe replacement.
Very expensive things: Catalytic converters (parts cost), heater core (labor cost). Let's hope these don't go bad. Not much you can do about the cat, but make sure you flush and change your coolant regularly and use only VW approved coolant.
