I've been noticing the fun designers have been having with detachable collars this spring. Having held onto a small vintage collection since I was a teenager, it's nice to see them as an easy way to alter a simple dress or top. Here are some beauties I've posted on one of my Pinterest boards.
From Louis Vuitton Spring 2012 Collection
Hammered metal via this etsy site.
Cloth beauty from etsy here.
A cute DIY version from here.