Rita's is a Philadelphia-based franchise chain of water ice/custard stands. In the New York City metropolitan area, the signs read "Rita's Italian Ice" -- don't worry, it's the same stuff.**

Water ice, at Rita's, is unique. Whereas Italian ices are more solid, almost like a very fine, creamy snow cone, water ice is looser and more fruity, made purely with ground ice, fruit juice, and pieces of fruit. (The exceptions are the chocolate and vanilla water ices, which have pureed chocolate and vanilla or something.)

With the handiwork of Robert and Elizabeth Tumolo, Rita's came to be in 1984, during a really hot summer in Bensalem, PA, a suburb of Philadelphia. Word travelled quickly, to the point of slowing the ice-cream-truck business; by 1987, the store had become a chain with the opening of its second location, and Robert's brother John had joined the business. In 1989, they opened the chain to franchising, and by 1998, they had expanded along the East coast from Florida to New York, and even as far west as Columbus, OH.

Eminently recognizable by their trademark red-and-white awning, Rita's stands offer not just water ice, but custard, cream ice (not quite ice cream), gelati (their version is a a layered combination of water ice and custard), and Misto shakes (a blended drink made from custard and water ice). While they carry several flavors of water ice and cream ice, they don't make all the flavors on any given day; they have a few regular flavors (which are there most days), but for the rest, you take what you can get (see below). All offerings are relatively low in calories and cholesterol; a whole quart of water ice runs you just 737 calories (no cholesterol), while a whole quart of cream ice is just 832 calories (.1 mg cholesterol). So not only is it tasty, it won't ruin your diet.

In short, if you have a Rita's near you, GO. If not, get near a Rita's. To quote their radio advertisements, (with a conga beat) "Be cool go to Rita's, be cool eat a Rita's".*** Incidentally, they have franchise information available on their website ("Be cool... OWN a Rita's"), and World Franchising purports them to be the fastest-growing chain of their type in the world.

A couple serving variations:

Try combining flavors for a unique taste, such as Cherry and Lemon, or Mango and Passion Fruit.
Try combining your favorite flavor with tequila for a fast, cheap margarita, or use rum for a daquiri.

Flavors:

Water Ice (* denotes regular flavor)

Cream Ice: Old-Fashioned Custard
** -- some people just don't get it.
*** -- the only thing I don't like is their advertising executive, who let that one go.
Sources:

http://www.ritasice.com/
http://www.review.udel.edu/archive/1999_Issues/05.07.99/index.php3?section=3&article=9
http://www.worldfranchising.com/Top50/Food/RitasIce1.html