With the July 2001 announcement of the intended flight of a second space tourist (Thawte Millionaire Mark Shuttleworth), here is a list of some companies involved in commercial launch vehicles.

Rotary Rocket Company

Developed the ROTON, a reusable capsule with propellar blades to allow a gentle controlled decent. The company liquidated in 2000 after several succesful test flights.
http://www.rotaryrocket.com/

Beal Aerospace

Texan company started by a millionaire hobbyist in 1997. Beal designed a traditional rocket engine with more thrust than the Saturn V. Beal Aerospace liquidated in October 2000 shortly after a succesful test of the BA-810.
http://www.bealaerospace.com/

Kistler Aerospace

Private rocket engine manufactureres. Awarded contract for NASA's second generation reusable launch vehicle June 2001.
http://www.kistleraerospace.com/

Xcor

Company with track record of custom aircraft design and rocket design. Xcor succesfully performed a manned-flight of the EZ-Rocket in July 2001. This vehicle has potential suborbital transport applications.
http://www.xcor-aerospace.com/