In Austin, Guadalupe Street between 21st and about 30th. The local equivalent of Telegraph Avenue, as it abuts directly with the west end of the University of Texas campus. Nobody ever calls it Guadalupe, except for aboriginal Texans in town for football games, and they pronounce it gwad-a-loop anyway.
Full of student and hipster types, gutterpunks, painfully hip little coffeeshops and ethnic eateries, used record stores, a Church of Scientology, and increasingly, trendy corporate franchise stores like the Gap and Urban Outfitters.
People-watching on the Drag is always a lot of fun, especially if you listen in on on some of the odd conversations which are always going on. But I'm not the first person to discover that; much of Richard Linklater's excellent movie Slacker was filmed and set in the Drag, and consists pretty much of people-watching and sitting in on interesting conversations.