Actually, any ice cream'll do, so long as it's from a funky old ice cream place.
If the nearest such funkiness is a creamery too far, or you're on a diet or not on good terms with dairy, check these non-caloric vicarious thrills on Flickr, Old-Fashioned Ice Cream Stands.
For a brand of drive-in you can trust, you can try The A&W Pool or Scrumpdillyishhus Dairy Queen!.
Do a search for one of my favorites, Tastee-Freez, or check out the T-F photos at agilitynut's supah terrific Roadside Architecture site.
Seek ye also the very frosty cool Tastee Treet.
For a meal as well as a snack, try The I Love Diners, Drive Ins, and Dives! pool.
'kay, enjoy--I'm gonna go eat some broccoli . . .