Crowd Seats may be the greatest site on the entire Internet. Mind you, that opinion is heavily biased, as I feel that any website that gives daily deals on sports tickets is instantly awesome.
Crows Seats is much like LivingSocial or any other daily deal site, except that it deals strictly in tickets to sporting events. The site sends out daily emails with offers for unsold tickets. Discount range from 50 to 90 percent off and can be shared through Facebook and Twitter, with each referral through the social media services netting you a $10 credit on Crowd Seats.
Unfortunately, Crowd Seats is only available for sports fans living in Los Angeles, San Francisco, New York, Boston and Chicago. Here's hoping they expand to more cities and are able to market tickets for all types of sporting events. Half-off NFL tickets would be too good to pass up.