Cabinet is the latest piece of software from Audio Ease, the company that brought you the highly regarded convolution reverb plug in Altiverb and Speakerphone. Cabinet (which costs only $60) is actually a basic version of Speakerphone and is geared specifically toward guitarists and bassists. This software is a set of five famous speaker cabinets captured using convolution technology for you to run your guitar or bass through.
If you don’t know about convolution and how it works, here are two wiki pages going through the basics: Convolution – Convolution Reverb