There are at least two artists with the name Madhatters. 1. An acapella Madison, WI based group (active from 1997 to present(?)). Their main last.fm landing page can be found here. Their website is UWMadhatters.com and they can also be found on MySpace. 2. Madhatters (EDM) are an Edmonton (Alberta) based Rock trio pumping out seventies blues tinged style meets Seattle sensabilities. The sound is earthy and honest with a loud mischievious twinkling wink and smack to the face. (active 2009 to present). Read more on Last.fm