Voodoo Doughnuts - Denver on Colfax Ave is utterly amazing. My daughter went to university in Seattle and those kids would drive to Portland, OR to get Voodoo - or "VD" as they would say. The only time I drove by the VD-Denver store and they didn't have a line around the block, I parked and tried to go in only to discover that they were closed. Another time, when I actually got in the front door, I discovered that there was another line inside that snaked around before you could put your order in. The couple in line behind us drove in from Kansas to get VD. You see people around Denver that display the iconic pink bumper stickers that say, "I GOT VD in Denver". Their donuts are pretty good. I think their newest store is in Austin, TX.
Trivia: Colfax Ave is the longest street in America -- 26 miles.