For shows, attractions & meals look for the booths situated at multiple locations along the strip called tix4tonight.  You can save up to 50% off the premium pricing that Las Vegas attractions demand.

Their business is simple, everyday there are several shows that aren’t sold out, and those tickets are discounted to you in a last minute call to fill them up.
If you are going to a show it might be worth checking both businesses out to see who has the best price of the day.