Upvoted for the fun idea. I strongly discourage anyone to actually use it though, captchas based on logos are very unsafe since you can easily crack them by performing a Google image search.
Spent way too much time in the "Try Me" section. Took this as a test of my metal knowledge rather than a query to test if I was human. Really fun product.
This would be a great product for the Metal Archives http://www.metal-archives.com/
Pivot