This is very usefull. Build with the help of the Greasemonkey creator.

<<One thing that got lost in the commotion of the extensions launch is a feature that is near and dear to my heart: Google Chrome 4 now natively supports Greasemonkey user scripts. >>

http://blog.chromium.org/2010/02/40000-more-extensions.html

Also
http://news.zdnet.co.uk/software/0,1000000121,40018131,00.htm