Rusty,
Clowns were one of the fish I wa initially thinking of, but they arent as hardy as some of the others fish that many people start out with. Nothing wrong with that, just ensure your tank is finished cycling before you add them. Keep in mind many clowns can get aggressive as they get older. The bigger clowns are more prone to this than the Occelaris clowns. Many stores will label Occelaris clowns as percula clowns, but they are in all likelyhood Occelaris. Clowns are damsel fish, so they can get territorial, keep that in mind. Its usually not to the same extent that damsels get though.
I would also stay away from the lawnmower blenny. Very finicky eater. I havent been able to keep one alive yet. Curtswearing has one but even he doesnt reccomend them to beginners.
Clowns, Royal grammas, certain wrasses etc would be fine for your tank. Anything labeled as "reef safe" by people you trust, will be a good candidate for your tank in terms of not being aggressive. The feeding requirements you may not be able to handle, but at least they wont be aggressive. Two fish I love, but are aggressive tank fish only, are triggers and the harlequin tusk fish/wrasse. Triggers are neat, but can really get aggressive, (Niger, and pink tailed triggers would be the two I reccomend in terms of least likely to eat everything else in your tank.) but have awesome personality. Same w/ Harlequins. Both of those fish types would be fine in a 55 (they get bigger but would still fit fine) but they eat crustaceans...so no shrimp or crabs in the tank, unless its food. Ive seen em eat cleaner shrimp too...so nothing is guarenteed. If you decide to go the trigger/ more aggressive wrasse route, eels are a good companion too.
All things to think about. Do you have those books or has anyone mentioned 'em to you? If not go get em @ amazon. I think you can order them thru RS here, but not sure just yet. The cool thing to doing that is that it shows amazon how many people frequent RS.....just a thought...
Good luck,
Nick