Google has developed an extension for Firefox that integrates with the social network Joga and allows you to view the latest scores from the World Cup, videos of the best goals, and talk with other fans about your favorite teams.
You can view the score of the latest match in the status bar. The extension will alert you when a goal is scored.
There's also a scoreboard that includes the upcoming matches and the most important news about World Cup. You can select the flag of your team to customize Firefox theme.
The best news about this extension? Google intends to release as open source the underlying framework and code they developed to build Joga Companion (that's the name of the extension).