This is a small graphic created by David Wildish (prints available HERE) showing the evolution of Doctor Who's sonic screwdriver throughout the history of the series. Which is your favorite? Mine's the first one, because it looks like the least painful to hide and retrieve from your anus in the event you're ever taken prisoner by the Daleks. *tapping head* Always thinking.
Thanks to Zin, who likes the latest version the best because the end kinda looks like a jelly bean.