Batman-and-bananas from DeviantArt created a fantastic springheeled set of cosplay boots as part of a steampunk version of Chell from Portal 2.

These started as two pairs of shoes, one cheap pair of black pleather boots and an old pair of canvas shoes. The heel 'spring' is actually plastic tubing as I could screw this straight into the heel to secure it firmly (plus a lot more sensible to walk in).

Steampunk Portal Boots (via Craft)