I really wish the Oscilloscope Watch had made it through the hassle of production:

http://www.gabotronics.com/oscilloscopes/oscilloscope-watch....

(Disclaimer: I'm one of the disappointed backers of his kickstarter campaign, which went nowhere...)

If there were another attempt at making a watch like this one, I'd definitely be a backer. I think this is really an ideal time for someone to start up an open-source, powerful watch platform ..