Here are some simple and neat concepts from South Korean design collective Monocomplex:
The Free Form Ruler is a measuring device that works like a pencil. The simple idea is that you'd drag the sensor tip along whatever curve or line you need the length of and the numbers are displayed via LED. Rotating the dial lets you choose the unit of measurement or reset it.

The Clip USB is a flash drive that you'll always have on hand and hopefully be less likely to lose, as it clips to your clothing.

The 2Face is a pair of eyeglasses whose color can quickly be changed by "flipping" the frames.

Dig their stuff? See more here.
Comments
at first it looked like a pencil that draws a dotted line - and a dotted line with adjustable spacing at that. Lemme know when you work out how that could function.
I'm just curious,what kind of sensor exist in reality technology could apply in this product (ruler)??
Mmh... This feels like I'm listening to a bad cover of a song.
obviously inspired by this: http://design-reaktor.de/produkte/02.html And if you can't improve an idea don't do it.
Also the digital ruler works (Graphite conducts) And the above idea is just a blue-sky-concept. Some photoshop on a picture of a pencil. I'd rather see a pic or video of a real product.
Anyone else also wish there was a pencil that would create dotted/dashed lines with adjustable spacing...?
Same technology as a Map Measurer?
http://www.google.se/images?um=1&hl=sv&rlz=1C1GPEA_enSE361SE361&biw=1784&bih=958&tbm=isch&sa=1&q=map+measurer&aq=f&aqi=&aql=&oq=
I haven't seen it used as a normal ruler though. Kinda weird when I think of it. I'd buy it.
Fluent/danial: In theory, you can combine the ballpoint pen with an ink applicator on a piston before the ink reservoir, and have that be adjustable through gears or something. Just a thought. Man, that would be cool.