browser overload

Can one ever have too much functionality in a browser? This person who installed 100 of the most popular Firefox extensions seems to think that one cannot. They wrote that

It was really extraordinarily stable. The work of hundreds of programmers who had no idea their code would be used together, coexisting happily in the browser.

I have fourteen extensions installed and that’s all I think I really need. I’d love to know others’ favorite extensions, so feel free to comment if there are any you can’t live without.