I recently bought an S&W TacPen:
This is a tactical pen (yeah, I know, I make fun of tactical stuff a lot). In true tactical form, it is both black and more expensive than a regular pen. They can be had at Amazon for about $26, substantially lower in price than similar products. As to what it really is, well, it’s a writing instrument and also a weapon. And it looks cool. It’s just over 5.5 inches long and takes Hauser Parker refills. Also, it is CNC machined from 6061 Airorated Aluminum and Type III hard anodized. I don’t know what that means but since this is a gun blog, I gotta use technical gun type words. It is solid, heavy and, in my limited testing, will go clean through a cantaloupe. Here it is compared to my EeePC for scale:
Here it is with the cap off:
And here it is field stripped:
In addition to slaying melons, it also writes really nice.
Quite happy with it.
ETA: Higher quality pics can be seen here.