Probably the most common induction motor that is thrown away on a regular basis is inside a washing machine, but once you start looking, they are all around you in a variety of sizes. When someone uses the phrase "induction motor conversion" they can commonly mean two things.
One is adding capacitors to store some energy so the motor will have some power going to the spinning armature just for start-up. Once started, the armature draws a small amount of power from the field coils to continue running. I've heard they need to be spun at 10% over the design RPM when using a motor as a generator, but I haven't tried this yet.
The other definition is when you take a motor and put permanent magnets on the armature to convert it into a PMA, which makes it useful for not only constant speed hydro/diesel/steam, but PMA's are the best way to harvest variable RPM wind energy.
The early promoter and engineer of PMA conversions of induction motors is a man named Zubbly, who has sadly passed away. Calling this a "Zubbly conversion" helps differentiate the two. I wish I could've met him.
Here's a couple links from my research file
http://www.qsl.net/ns8o/Induction_Generator.html
http://www.allaboutcircuits.com/vol_2/chpt_13/7.html
adding capacitors to make an induction motor a self-excited generator/welder
