Visual nitpick - the tags are very distracting. When I scroll through a page, I want it to be static so my eyes can follow what I'm doing. Things popping in and out of existence really jars me. The tags' color doesn't seem to mesh well with the rest of the site either.
Yeah, the tags do seem a little disconcerting when scrolling. I felt like they made the site seem a little too busy if they are constantly on display, but I thought they'd be useful for jumping to interesting topics from the front page, like ptn suggested below. I'll figure out a better way to present them. Thanks!
Other than that - great idea. Best of luck!