Renters of a condo above me caused damaged to my property; how do I track down the absentee owners?

Go to the assessor's or tax collecto's office, there should be a record of the owner's address.  See just where the tax bill is being sent to.  If that doesn't work for some reason, try the condo board, they may have the owner's address as well (someone is paying the condo fees).  Finally, depending on your relationship with the renter, see where they are sending their rent payments.

One other thought, you could try and google the owner's address.  In fact, there are even search companies that do this for you on-line for a modest fee.

Best of luck.