I had several people ask me through my blog or email to write a version for Google Chrome. And, by popular demand, here it is! To my surprise, it took much less than I had originally thought. I had a few small problems though, from the event handlers, different from Opera UserJS model, to style attributes for dynamically created elements, and other minor things as well.
It's still lacking Ajax/xmlHttpRequest support, but that shouldn't be a huge problem.
The code, as usual, is up on Github
If you try it, I would be interested to know what you think. Have fun!