$19 for a Day-Spa Pass at King Spa & Sauna (Up to $30 Value).  Modeled after traditional Korean spas, King Spa and Sauna houses nine distinct therapy rooms, each of which specializes in treating a different form of ailment or anxiety.  You may buy multiples and services are transferable.

Groupon always sells thousands of these – I really, really like the idea of spending an entire day here – obviously others feel the same since King Spa charges $5 if you stay past 2 am!