Simple answer: I get bored.

Long answer: I have a lot of time on my hands (hope the 'rents don't read this) so I end up thinking of ways to modify products to add or change their functionality. As I have more time (and more money) I will try to sell my creations (maybe thru ebay) in order to fuel my work. Each project ends up costing between $30 and $70 which adds up quickly. Some of my mods are inspired by the need for laughter, others, sheer boredom. Everything I modify/create is functional in someway. I'm taking two or more things things that shouldn't be together, and merging them in a way that both can be used.