Well Jeroen Breebaart did it again. He added the excellent Omniverb plugin to his impressive free collection:
http://www.jeroenbreebaart.com/audio_vst.htm
Omniverb is a reverberation plugin with separate control of the reverberation time, echo density, room size, and early reflections. It can also be used as a gated reverb.
The incredibly low CPU usage is amazing for this kind of plug. And the sound is great.