SimulAnalog Guitar Suite:
Classic analog amplifier sim
The free SimulAnalog Guitar Suite is a VST plugin collection of accurately modelled analog amplifiers and other classic processors for guitarists. It contains the simulation of the two classic guitar amplifiers the Fender Twin 1969 and the Marshall JCM900, as well as the VST simulation of the following stompboxes: Boss DS-1, Boss SD-1, Tube Screamer, Oberheim PS-1, and Univox Univibe. The Guitar Suite VST plugin doesn't have a GUI of it's own, but what it lacks in appearance it makes up for in sound quality. Especially the JCM900 and Boss sims are higly recommended!
If you're not happy with the standard GUI of your VST host, you can also download Requietus'
(as shown here to the left) for the entire SimulAnalog Guitar Suite.