D100
Take that, D50's.
They're useful when you really want to take 5 minutes to find out if you hit something in Dark Heresy. In other words, better just use a pair of D10's like a normal human being.
Apparently it took about 6 years to make this die. I guess this means that it takes 6 years to put the numbers 1-100 on a fucking golf ball.
Usage
It may seem awesome when you see it, but as soon as you get one (and whoever's selling it to you is also aware of how unspeakably lame it is, and will probably even tell you) you will find that it has two major flaws: it takes about a minute to stop fucking rolling around and if you aren't blessed with a perfectly level playing surface you will never find out exactly what you've rolled (and when there are six other numbers right next to the 100 and 1, that's a pretty big problem). Oh, and to top it off, it isn't even very balanced, so it's effectively a loaded die.
On the other hand, if you hate your friends, show up to your next meeting and sweep all the d10s off the table, then drop your d100 right in the middle with a theatrical gesture and watch as everyone is mesmerized by its incessant rolling (see: takes about a minute to stop fucking rolling around). Take this opportunity to pocket the d10s, run away and never come back.