What's this special type of PCB prototyping board called?
Radio Shack calls them various names such as "Universal Component PC Board" and "Multipurpose PC Board"

On Digikey you can search for Prototyping Products - Prototype Boards - Perforated, and under the "circuit pattern" selection you will find items listed with Common Bus (runs the whole length of the board), 3 Hole Pad (sounds like what you are looking for), 2-Hole Pad, etc.

Hope this helps.