I went with brisket for Memorial Day Weekend (also grilled ribeyes last Friday). But the brisket takes about 9 hours. My favorite "6 hours or less" smoker options are salmon or Tri-Tip. The tri is always a hit in our house, and here is a great recipe for it. Smoker-cooking.com has a LOT of great recipes (where I get my brisket, pulled pork, ribs, and turkey rubs/marinades):

http://www.smoker-cooking.com/smoked-tri-tip.html