Martin Eastwood has released MVerb, a free reverb effect.
Digital reverb has always been something of a dark art as there is very little information publicly available and most of the big companies releasing reverbs are very vague about the techniques they use. The only real example is Freeverb so I though I would share some code for a reverb that sounds pretty nice and is very low on CPU usage. It is based on the figure-of-eight reverb structure suggested by Dattarro, which uses a bank of allpass filters to smear the phase followed by a loop of multi tap delay lines that feedback into themselves to create echoes. I have also added another delay and a mutitap delay to act as predelay and early reflections. The early reflections still need a bit of tweaking but they do the job for the moment.
The code is written in C++ and is available under the GPL license. It is really simple to use as it is all contained in one header file and should be cross-platform. There is also an example showing how to use it in a VST plugin.
MVerb is available to download as a VST effect plug-in for Windows PC. The source code can be downloaded as well.
More information: Martin Eastwood Audio