The Theater of Living Arts on South Street in beautiful downtown Philadelphia is almost always referred to as simply "TLA." Usually this is used as a musical venue, although I hear they used to show movies. It is a rather small place that reminds me, in terms of size, bands, and clientelle, the 9:30 Club in Washington, D.C. and the Club Congress in Tucson, Arizona. These clubs are large enough to host known bands, but small enough to still feel intimate.
Off the top of my head, I can think of the following bands that have played here recently: Cibo Matto, Blonde Redhead, Placebo, Pork Tornado, The Roots, David Byrne, Crash Test Dummies, Pharcyde.
The Theater of Living Arts is owned by the Electric Company, which is another much larger venue also in Philadelphia, and does not actually generate electricity. The Electric Company hosts much more popular bands, and feels much more like an arena than a club.
Around the corner from TLA there is also TLA Video, an affiliated video rental outlet, which is the only local competition to the corporate monolith Blockbuster, also on South Street.