Some groups which "do" Rapid Prototyping

Infinity Software Development, Incorporated

A company which offers to create custom software for clients, using a rapid prototyping model.

Prototype Express

I usually don't include negative examples, but this Web site is so bad I just had to put it in. It looks like two guys in a garage, but judge for yourself.

Rapid Prototyping Corporation

In industry, "Rapid Prototyping" also refers to the process of using computers to control sophisticated machinery which creates plastic prototypes directly from CAD (Computer Assisted Design) files. This process eliminates the traditional process of having a machinist create prototypes. It's cheaper, more efficient, and reduces human error introduced by the machinist. (By the way, it also puts machinists out of work).

The University of Helsinki (Finland)

Hannu Kaikonen divides Rapid Prototyping into two parts. Rapid Prototyping is the process described on this Web page. Kaikonen refers to the building of models from CAD design (see above) as "Rapid Tooling". It's an interesting and useful distinction.