One of the reasons that I haven’t switched my main browser to Chrome is the lack of extensions.  Chrome has been great for running JS-intensive web apps, but for everyday stuff it just can’t keep up with all the functionality that Firefox gains from having extensions.  This is actually the main reason I haven’t switched; the main other one is poor SSL client certificate support, which is important because MIT uses that a lot.

Well, now that Chrome has extension support and extensions are starting to come out, I’ve decided to see what extensions are available, and how well they can replace my Firefox addons.  First, a list of the Firefox addons that I use a lot (also, made into a collection at https://addons.mozilla.org/en-US/firefox/collection/kmod ), roughly in order of their importance:

• TabKit — probably the greatest addon I use.  It completely changes the way tabs are displayed by putting them on the left and organizing them into trees.  Seriously, if you’re using a lot of tabs in Firefox, check it out.
• AutoPager — I’m really glad I stumbled upon this.  I find it very annoying when sites paginate their content excessively.  Also, loading up the next page of Google results is annoying (but who does that?).  What AutoPager does, is it automatically loads the next page of results/content as you scroll down.  It’s usually fast enough that you don’t notice any lag between scrolling down and seeing the content there.  Again, this is an extension that you should have if you do a lot of browsing in Firefox.  You won’t know that you need it, but once you have it you’ll be consistently impressed by how much nicer it makes things.
• Flashblock — I wasn’t sure for a long time that I’d want to block all flash on all pages, but once I tried it, it’s really nice.  Usually the one thing that slows my Firefox (or Chrome) to a halt is all the flash that gets running, even if I close all the tabs with flash!  Now, I really don’t trust Adobe enough to write good software (neither should you), so I have no problem blocking them.  And my browsing experience is now much cleaner (and no more stealthy flash cookies either)
• AdBlock Plus — Browsing with ads?  I don’t think so.  Some people say that it’s unethical to block ads, since that’s how sites make money.  But given that 1) I’ve never clicked on an ad, and 2) I’m not going to buy something based on seeing an ad, I don’t see what anyone is losing.  I’m getting a better browsing experience, which is good for me and for the sites that I’ll visit more, and it helps advertisers save bandwidth.
• Xmarks — I don’t know, I don’t feel like this is a good piece of software, but the service it provides (bookmark syncing) is just so useful that I find myself using it.  Perhaps I’m just blaming it for bugs that they’ve had in the past (that they may or may not have fixed), but if a better bookmark sync tool came out I’d use it.
• Firebug — Not part of my daily workflow, but when I need to debug websites, Firebug is invaluable.  But I’m sure that if you need it, you already know about it

Alright, so those are my main Firefox extensions.  They almost all now have Chrome versions; how do they stack up?

• TabKit — no Chrome version!  And likely won’t for a while, until Google/Chromium greatly increases the extensibility of Chrome
• Autopager — the Chrome version seems pretty good.  Maybe it doesn’t support all the sites the Firefox version does, but I haven’t been able to notice.  [Update 5/14/10 — I’ve had to disable this, because it excessively slows down doing Google searches, which is unacceptable.]
• FlashBlock — also seems pretty good.  I think it’s missing some of the Firefox version’s features, but I don’t use them anyway.  [Update 5/14/10 — I now use this version instead, though they do the same thing.]
• AdBlock — again, seems to work pretty well.  I haven’t tested if it blocks everything that the Firefox version can, but it seems good.
• Xmarks — Oh god, even buggier than its Firefox version.  The nice thing is that it uses the same database, so your Firefox bookmarks should (in theory) sync down to Chrome as well.  I’ve had a lot of problems with this extension; only use it if you really need your Firefox bookmarks, or Xmarks has gotten its act together.  [Update 5/14/10 — They’ve fixed the early bugs with the Chrome version, and now I find it on par/perhaps better than the Firefox version.]
• FireBug — I’ve heard there’s a Lite version for Chrome, but I haven’t had reason to use it yet.  I would speculate that it’s a decent version of FireBug, but it’s missing some core features of FireBug on Firefox.

So in summary, most of the extensions I use in Firefox have shown up in Chrome.  I’m sorely missing the presence of TabKit, but the browser is noticeably faster, even with the plugins.  So I’ve changed my workflow now so that I spend most of my time in Chrome, but I still do have to switch back into Firfeox fairly often.  I’m not going to get into which browser is “better”, but so long as Chrome can’t do everything that I’ve come to expect Firefox to do, it will never be elevated to the status of a “primary” browser (even if I do make it my default).