High heels to low heels, instantly
Sophie Cox, while a student at North Sydney UTS a few years ago, invented these nifty shoes for the Australian Design Awards:


These “simple, innovative” heels can convert from “a high 7 cm heel to a low 3 cm heel with one simple twist on/off action,” according to Gizmag. Very cool.
Reselling your heels on eBay …
When I used to work for Auction Boulevard in California, we used to get in ALOT of shoes to put up for people online … it was amazing how well they sold and that people actually got back what they expended in their shoe collections. The key: lots of pictures for all angles, the sizes, the measurements, and be as descriptive as you can to promote the shoe. Links to the manufacturers web sites are also very recommended. Good luck and good sales!