I actually looked up recovery rides this morning for myself and this is what I found that was straight to the point. I usually do one the day after a very hard ride. I'm very new to riding but thought since I had this bookmarked I would share.

Description: Recovery rides should be between 30-120 minutes in length on flat to rolling terrain. Keep your pedal speed around normal, staying in a light gear to keep resistance low. Heart rate must also remain low even if you hit any hills, just slow down and use your gears to keep the resistance low. The key to recovery rides is to ride just enough to engage the active recovery process but not long or intense enough to induce a training stress upon yourself.

Purpose: To speed the recovery process by riding at an easy pace at low resistance on flat terrain. Benefits include increasing blood flow to the muscles to help remove muscle soreness, reducing free radical and lactic acid buildup that causes muscle stress and damage. Studies have shown that active recovery at an appropriate pace leads to faster recovery than complete rest.

Here is the link I quoted from...
http://www.t2r.org/train/workout_definitions.htm