Wavefront's AL3201B "Digital Reverb Engine" is a versatile IC for generating a wide variety of reverb and other sonic effects.
The IC has 16 built-in reverb effects, all designed to be useful and robust in a wide variety of products, including guitar amplifiers, effects mixers, and karaoke systems.
A separately available development system allows creation of additional effects.

All this for under $6 in a 16 pin SOIC package!