Browsing the Web with Javascript error notifications turned on
You don't really realize how sloppy and incoherent Javascript is right now until you turn on error notifications in your browser. I do it to QA our 
products, but the fact is it almost makes browsing the Web unbearable. It's pretty amazing to see how many widely used sites throw Javascript errors left and right, relying on the browser to gracefully ignore them. I know most users don't have Javascript errors turned on, but come on, should commercial software really RELY on that? Don't commercial sites have testers/test suites/self respect?
