Here's a simple pattern that I found while doing a Google search: http://uptownangler.com/flies-quality-flyfishing/best-bonefish-flies/sand-flea-fly.html
Looks like some white Estaz, foam, bucktail/calftail, and some dumbbell eyes and you should be set!
More: http://musicarskikafe.blogspot.com/2010/01/little-shrimps-and-sand-fleas.html
"OBX Clousers" work well also: #2 or 2/0 black over orange with copper flash or black over red with copper flash. Plucked a small flounder out of the surf last year with one of those!