According to Wikipedia, Iridescence (also known as goniochromism) is generally known as the property of certain surfaces which appear to change colour as the angle of view changes. Iridescence may be seen commonly in soap bubbles, butterfly wings and sea shells.
Musn't forget party dresses! I just listed this red/black iridescent taffeta dress on eBay (here) and marveled at how happy this fabric always makes me. Every time I see it I have to move the fabric to watch the color change.
I decided to start trying to collect some images of iridescent clothing I've sold and am selling. I'm working on a new Flickr set:
If you need further inspiration, how about these iridescent lovelies from Etsy vintage sellers:
(deleted due to all being sold!)
The weather's changeable, so why not your dress?