Good free reverbs can be hard to find. Here’s a popular reverb VST that that rivals the quality of commercial units and best of all it’s free (or at least donation-ware).
Features: Separate dry/wet controls, reverb time and room size parameters, width control for setting mono/wide stereo and pre-delay functionality.
You can adjust the quality for lower CPU usage and the ‘Variation’ button creates a new variant of the same room. There’s a damping section to control bass and treble and an excellent EQ section for filtering unwanted frequencies.
As mentioned, this is donation-ware meaning you can pay what you want for it (there’s a nag screen at start-up until you register it on some versions).
PROS: Studio quality, lots of tweakablity
CONS: A nag screen, but who cares really.