Frontier slashed prices on many routes for travel between Apr. 15 - May 31, 2011.  Travel is valid any day of the week except Sundays.  Peak travel around holidays, like memorial day weekend, seem to be blacked out on most routes.  Since this sale is unadvertised, it could disappear at anytime.

Sample fares include:

Columbus to Denver $228 round-trip

Washington D.C. to Los Angeles $268 round-trip

Minneapolis to Las Vegas $198 round-trip

Chicago to Phoenix $238 round-trip

Denver to Boston $188 round-trip

Indianapolis to Fort Lauderdale $158 round-trip

Dayton to Los Angeles $198 round-trip

Pittsburgh to Santa Ana $164 round-trip

Portland, OR to Tampa Bay $248 round-trip