I discovered A Fine Grind not long ago when my friends and I were wandering the Marshall area. They make the best latte I've had in the Cities, and their Frappes are divine. I recommend the "Dirty Uncle Chester", a mocha frappé with toffee syrup. They also offer food, such as really awesome muffins, cookies, and paninis.
Best of all, even with its very reasonable pricing ($3 for a latte) this coffee shop has frequent promotions, such as $3 Frappé Fridays. Beware, however; you'll be charged an extra $.25 if you pay with a credit card.