Believe it or not, there once was a time when desktop computer hardware didn't have the muscle to do convolution reverb along with simultaneous audio processing such as is needed in a multi-track DAW program. And without convolution, your on-board reverbs were limited to being based on fixed samples of acoustic spaces or pre-existing reverb units. Sure, you had control over parameters, but without convolution, you couldn't use impulse responses to create your own models or samples of acoustic space - real or imagined. A nice example of how to do just that (yourself) can be found at Gearwire here.

Convolution is at its base a sampling technology, and where there's samples, there's sample libraries. Italian publishers Morevox have released RetròVerb, a collection of impulse responses, meant for use with any convolving reverb plugin or program such as Altiverb or Space Designer. Check out the demo clips here and notice the differences between the frequency response of the various reverb tails. These are not changes in parameters, they are each different acoustic spaces as represented by differing IRs.

The $60 Morevox RetròVerb Library brings you over 100 models of real space, vintage reverb gear and custom IRs for special purposes.