Yogurtland is quick and easy for a fro-yo fix. If you scan the code at the register they will usually give you a free ounce, which is always welcomed in my book. You can also show them that you've checked in via Foursquare and it works the same way.
Depending on the location, they have a great variety of flavors, but the problem I've found is that the actual machines dispense slower than molasses; which of course is undesireable.
The decor is fresh and there's always a great energy at each location. I really like the global checkin they have at some of the flavor stations. :)