The longest line I've seen at Shake Shack yet was yesterday. There's waaaay more people to the left of the picture that didn't make it in the shot. (image by: vivien chin)
I'm a huge fan of In 'N' Out Burger on the west coast, but since I can't get those here in NY I go to Shake Shack. Their burgers, fries, and concretes (ice cream) are excellent. They have 2 locations. One "shack" is in Madison Square Park seen above and one on Columbus Ave. @ 77th St. The line is often really long at the MSP location, expecially on nice sunny days like yesterday, but if you're really craving it then it's worth the wait. You can always check out their ShackCam on their site which shows a live feed of the people in line. Atleast you'll know if it's going to be a long or short wait. I usually go to the Upper West Side location since it's in my hood and the line isn't as long. Another cool thing about the buildings are that they are completely Wind Powered. Yay for being green!
Typical Order for me: Shack Burger and Fries (and an Upper West Slide Concrete if I'm feeling super hungry)