Just got a pair of these knee guards in the mail after reading a very informative review on Webbikeworld. Here's the link to it:
http://www.webbikeworld.com/r4/thor-knee-guards/

After going for a short ride on some twisty canyon roads near my house, I am very happy with them. When I first put them on, I thought they were a bit on the hot side, but they fit well and I was able to slide them under my fairly skinny boot cut jeans without any issues. The jeans also helped to keep the flexible upper knee portion in place against my kneecap. They feel a bit cumbersome when walking around, but once you start riding they feel very comfortable. I barely felt them, and having the extra protection is always nice for peace of mind.

I plan on making these a more permanent piece of my everyday riding attire. I got mine off of Ebay for $30 shipped, but if you are thinking of picking some up as well, make sure you get the Adult size and not the Youths. Thoughts/Opinions/Concerns anyone? Post away.