One of my favorite projects is a favorite not for its complexity but for the effect it provides. In “Let’s Rumble” from MAKE Volume 02, Craig Engler shows us how he added bass shakers to his home theater chairs to pump up the movie effects. I’m not much of a movie buff, but I love me some bass. Ready-made, commercial shaker systems are pricey. Craig experimented and found what worked best for him. Granted this piece was from 2005, so prices for components have gone up a bit, but you can still piece together this system for way less than a commercial package.
You can also still pick up a back issue of MAKE Volume 02 (classic!) at the Maker Shed.