You could also create a similar Greasemonkey script (or user script/style) restricted to google.com that could be easily enabled/disabled from the interface.

Yet another way would be using Adblock Plus. If combined with with ABP Element Hiding Helper, removing webpage portions is a peace of cake.

I know that both ABP and Greasemonkey can be site-specific. Can userContent.css changes be similarly context sensitive?

Good question. Searching a bit I found a syntax that works, without any extension or so:

-moz-document url-prefix(http: //www.google.com/) {

body { background-color: green!important }

}

This will turn the Google homepage green.

[blank added in Google URL to prevent auto-linking; a blank before the exclamation mark was removed by the forum...]

If there are occasions when you like the Google search page, you could save it on your computer. You could then and in the future use that local copy which you like. Before you save a copy to your computer, you may want to sign out of your Google account.

If you never like Google's search page or are concerned about copyright, you could write your own search page or use one written by someone else.

http://blogoscoped.com/blackandwhite/
http://findforward.com/