When I’m too lazy to search Stubhub or when I just need something fun and cheap, there’s Goldstar to lend a reduced-price hand. Discounted (and once in a while free (with a small service charge)) things to do in most metro areas. Cirque du Soleil shows, concerts, Disney On Ice, comedians, plays, tours, NFL/NHL/MLB/NBA games and lots of other attractions.
Events for less popular show times are sometimes heavily discounted. Luckily I live near San Francisco so there’s always something going on in the area. I’ve paid nearly half price for a few different Cirque du Soleil shows (on weekday evenings) and enjoyed every one of them. Same show, half the price!