Re the bias bit, I do keep checking the featured section of the Firefox extensions. For the longest while, it's been YouTube flash-html5, YouTube all html5, chatzilla, multi links plus. Oh and Gmail notifier.
The chrome extensions on the other hand.
Speedtest, sharepad (notepad extension), an extension to search for any spoken word in a video (nice!), an extension that highlights vertical rhythm in a web page (cool). I wouldn't say they've seen a lot of variation either but they have some cool tools and that's just the extensions.
I do get that I'm probably seeing announcements only on chrome related stuff though. But I wish Firefox would make up for it by tweaking their store to help us find fresh stuff.