Greasemetal - Greasemonkey analogue for Google Chrome
So far (the current version is 0.1) Greasemetal may be of interest only to advanced users, since it does not contain a UI for managing scripts (you must manually copy the necessary scripts to the appropriate folder).
Greasemonkey functions are also not supported, therefore it is recommended to use scripts that work not only in FF, but also in Opera and Safari.