I saw the commercial for the Goody Spin Pin several wks ago and I was so intrigued I went out the next day to purchase it. If you want to achieve the perfectly loose, messy bun/updo then these should be your weapons of choice. So easy to use and the 2 little springs actually hold up my hair all day without any loosening (for a looser 'do, I use one). The je ne sais quoi hair we've been vying for, all for $5.99...
Go get these asap. (comes in blonde or brunette)
P.S. Another plus - after you've had your hair in a bun with these for a few hours, you get soft, pretty, loose waves.
[UPDATE]: I received some emails, tweets and a comment about how this thing works. Basically you twist your hair, then you "screw" one of the pins in by turning it into the bun clockwise. You do the same with the other one but on the opposite side. To take them out, you just turn them counter-clockwise. (instructions are included in the package)