I just discovered this Firefox plugin called FireCoin
. I allows you to support a website by easy donations. A site with specific meta information will allow the plugin to identify a Bitcoin address to send bitcoins. There's optional meta support for a description and "thanks" redirect.
I think it's a good start, but needs support for locating other bitcoin addresses on pages (like forums) to support helpful forum members (where, perhaps, the bitcoin uri scheme/links are not present or can't be implemented).