This is currently Firefox's strength. There are literally thousands of add-ons for Firefox today, over 1,000 in web development alone.
But by concentrating on niches, and signing exclusive deals, so the add-on makers work only on Chrome, Google is taking small but telling bites of the market.
The media is already flocking to one such deal. But a second extension better illustrates the trend, and it's called (naturally) extension.
Extension.fm finds mp3 files on pages you visit and indexes them into a personal music library. This is a seriously cool thing for people like my own son, who loves to regale us at dinner these days by showing the latest music video he has found.
At 19 he's never gotten into iTunes, and many feel the Apple-Google rivalry will define music in the future. It's the next evolution in the music business, from music you own to music you find. And the one rule of music is you want to be where the young folks are, not where I am.
Extension is the kind of game-changing add-on that can move browser loyalties. My son has been dismissive of Chrome in the past. When I tell him of this he won't be, I guarantee.
And that seems to be the strategy. While Firefox acts like a typical open source project, listing whatever comes in, working with everyone, Chrome acts more like a proprietary outfit, strategically.
This is a key difference between Google and most open source companies. Most are looking to build an ecosystem however they can get one. Google can be more careful.