Of course, you can also watch TV online for free! If you're looking for an old episode -- or, in many cases, even a day-old episode -- you can probably find it just by entering the name of the show into a search engine. Hulu, Bing and YouTube offer extensive libraries of TV shows through streaming services.
YouTube generally offers clips of shows and links to full episodes on network Web sites. Bing links to episodes on Hulu with a short commercial introduction. Interestingly, through Bing, you can even see first-run episodes of shows by spending little more than a few seconds watching a commercial at the beginning of the show.