Virgin America currently has selected flights starting from $79 flying from SFO! Book by July 18, 2011. Fly between August 18, 2011 to November 16, 2011. Restrictions apply, see below.
Here are soeme cheap Vegas flights.
Monday, Tuesday, Wednesday, Thursday, Saturday = First Price
Friday, Sunday = Second Price
San Francisco Las Vegas $79* $89*
New York Las Vegas $169* $189*
Many other cities are available but I only posted the Vegas flights.