LA Stage Tix has a number of shows with tickets at half price, including:

10 Min Play Festival (now in its' seventh year)
Fire Rose Productions (1/7/2010 to 1/17/2010)

11, September
Breadline Productions (1/8/2010 to 2/7/2010)

THE 25TH ANNUAL PUTNAM COUNTY SPELLING BEE
La Mirada Theatre for the Performing Arts (2/5/2010 to 2/21/2010)

bobrauschenbergamerica
TheSpyAnts (1/21/2010 to 2/28/2010)

Camelot
Pasadena Playhouse (1/8/2010 to 2/7/2010)

The City
The Group Rep at the Lonny Chapman Theatre (1/22/2010 to 2/28/2010)

Confusions
The Lost Studio (1/15/2010 to 3/7/2010)