Plugins for Chrome?

I'm interested in what it would take to develop custom plugins for Google Chrome. Has anyone looked into this, and if so, is it possible to create something like Adblock/NoScript or at least Greasemonkey?

I'll be frank about my intentions here... I would first and foremost like to see Chrome subverted to serve users (like me) before anyone else (including Google). I have grown accustomed to an ad-free, relatively secure browsing experience with Firefox. However, a Greasemonkey-like interface would also have some interesting implications for doing more on the client side than was possible before due to V8's performance.