Poor Plate is free and is available for Windows as a VST effect plug-in and Mac OS X as an Audio Unit effect plug-in.

Controls:

• Dry Level: the level of the original signal, off - 0db.
• Wet Level: the level of the reverb signal, off - 0db.
• Pre Delay: pre-delay in milliseconds, 0-120.
• Decay: decay rate, i.e. how long the reverb tail gets,0.0 - 0.9.
• Decay Diffusion: amount of diffusion of the reverb tail.
• Input Diffusion: amount of diffusion of the input signal.
• Bandwidth: input signal bandwidth, in Hz.
• Treble Damping: damping of treble in reverb tail, in Hz.

vacuumsound also offers two other free VST/AU plug-ins, which were released several months ago:

• ADT - Artificial Double Tracking is a plug-in which emulates the "Artificial Double Tracking" technique invented by The Beatles at Abbey Road Studios. It takes a mono input signal and generates a stereo signal with the original signal panned to one side and the ADT signal panned to the other.
• The RIAA - Phono Equalization plug-in provides normal and inverse RIAA equalization. It thus can be used for record playback or vinyl cutting purposes. Another nice trick is to use it to simulate certain 'vinyl sound effects' by applying the inverse RIAA curve to your signal and after running it through a compressor converting it back to flat.