Many more PT Boats than you can imagine. Check the offerings from White Ensign's Narrow Seas line.
This is their 80-foot ELCO sold as the PT-109. It is 1:350 scale resin & brass, complete with anti-depression rails and a 37mm anti-tank gun. This is my build of the kit in their catalog.
http://www.whiteensignmodels.com/acatalog/index.html?http%3A//www.whiteensignmodels.com/acatalog/Online_Catalogue_1_350_Scale__Narrow_Seas__Kits_38.html&CatalogBody
WEM also makes a 77-foot ELCO sold as the PT-34. It is an early PT Boat with twin turreted machine guns under plexiglas canopies.
Iron Shipwright makes a late-war 80-foot ELCO, with roll-off torpedos
ISW also makes a series of Spanish-American War-era Torpedo Boats
JAG makes a 78-foot Higgins
If 1:350 scale is too large for you, WEM offers the PT-109 in 1:700 scale. Yes, it has all the PE details offered in the larger cousin (depression rails in 1:700 are a real trip!). PitRoad also offers a set of styrene 1:700 scale PT Boats.
Now if you wish to discuss Schnellboats or MTBs ...