Enormous outdoor flea market on the north side of Las Vegas. If you're looking for a more local experience and a fine way to waste an afternoon, then check this out.
Highlights include great people watching, live music, tons of food vendors and, of course, an incredible amount of junk to buy. Unfortunately, a lot of the stuff can be found at any dollar store, so it's nothing special. However, if you dig you can find some gems (example: old slot machine marquees for $5 each).
Bring cash and come early. It gets crowded on the weekends.