This is an interesting concept. For users of Google Reader, this browser plugin / extension replaces the existing design (css stylesheet) with one which uses helvetica, and strips out a lot of the advanced functionality which your average punter wouldn’t use. It makes the whole experience much simpler and pleasing on the eye.

There’s already a load of scripts out there which improve the functionality of pages (Greasemonkey etc) but this is the first i’ve seen which focuses on just altering the design. There’s probably a campaign in there somewhere… for a game or movie theming every site you visit for launch week with a special colour scheme.