www.Convertible-heels.com

Here is a quick sketch I made for the "Day 2 night heels" team at Startup Weekend Boston, summer 2009.
From their website:
"Day2Night has come up with a revolutionary solution to the problem of comfort and functionality versus style: CONVERTIBLE HEELS. Our heels, wedges, and boots come with heel attachments of varying heights that can be easily attached to increase your height or detached and replaced with smaller heels for a more comfortable trek."