I would suggest running affiliate programs for ticket resellers (stubhub, ticketsnow, etc) ... they can be quite lucrative depending how many sports events are in the region that your visitors come from.
Another idea would be to integrate eBay auctions that sell sports memorabilia - the ebay partner network pays 50% of their sale fees in commission and a variable rate for new eBay members you refer.
Have a look at Commission Junction to see many event ticket affiliate programs.
Cheers,
Rob