Hot, bad cooking at the net's edges

Companies like Google work hard to reduce data center energy use (they should be made to work even harder via a carbon tax!!!) but what about energy use at the edges? Russell Coker:

Web standards are complex and it’s difficult to do everything the way that one might desire. Making a web browser that doesn’t take 100% CPU time when the user is away from their desk may be a difficult technical challenge. Designing a web site that doesn’t trigger such unwanted behavior in common web browsers might also be a challenge. But when one company produces both a web browser and some web sites that get a lot of traffic it’s rather disappointing that they don’t get this right.

Action:

The consequences of such wasted CPU use are reduced CPU time for other programs which might be doing something useful, extra electricity use, and more noise from CPU cooling fans (which is particularly annoying for me in this case). Any suggesstions for reducing the CPU use of web browsers, particularly when idle?