Even without extensions, Google Chrome's market share grew phenomenally during its first year. Now that the No. 1 most-requested feature comes baked into the Windows (beta and development) and Linux (beta and development) versions, it's time to look at some of the best extensions available for the upstart browser.

Google Chrome's extension manager. (Credit: Screenshot by Seth Rosenblatt/CNET)

The No. 1 extension on my list is the No. 2 most-requested feature for Chrome: RSS support. The RSS Subscription Extension allows Chrome to automatically detect RSS and Atom feeds on a page. It's not entirely clear why this isn't a default feature since it's part of every other browser, but at least now there's a way to add it.

There are a host of Google-service related extensions, all based on letting you know at a glance if there's an update for you to check in on. The Google Alerter covers Gmail, Wave, and Google Reader, although there's also individual support for them as the Gmail Checker, Google Wave Checker, and Google Reader Checker. There's a Google Calendar Checker, too.

The Google Translate extension adds a slick pop-up toolbar. (Credit: Screenshot by Seth Rosenblatt/CNET)

The Google Tasks extension hides your tasks behind a button that opens a list of them when clicked. The most useful Google-related extension is for Google Translate, which will offer on-the-fly translation of a site that doesn't appear in your default system language.

Expect security to be as big a subcategory of extensions for Chrome as it is for Firefox. Popular and effective secure personal password storehouse LastPass provides a safe and near-universal way to manage your passwords, making them easily accessible without compromising their integrity. LastPass also supports Firefox and Internet Explorer on Windows, making it an excellent one-stop solution. When Chrome's extensions get activated on the Mac version, the reasons for using LastPass will become even more compelling.

LastPass options in Chrome. (Credit: Screenshot by Seth Rosenblatt/CNET)

Also cross-browser, Web of Trust evaluates Web sites based on consensus. It may sound counter-intuitive to some, but it's proven in the past year to be an especially effective tool for determining whether you can trust that sketchy link you're thinking of clicking on.

UnShorten.com is one way to see what that shortened URL is hiding, but ChromeMUSE is another. This useful extension not only can shorten URLs via several different shortening services, it can also expand embedded short URLs automatically.

FlashBlock is a good way to kill Flash and Silverlight-based content. It leaves a blank spot where the ad or embedded video would've been, which you can then selectively load by clicking on it.

Despite the name, AdBlock+ should be avoided. It's not made by the same publishers who manage AdBlock Plus, the popular and effective ad-blocker for Firefox. This is actually a fairly serious problem with Chrome's extensions, where unknown entities are appropriating identical or similar names to well-known and trusted Firefox add-ons for what amount to nefarious purposes. So far, the ad-blocking extension that most users seem to be trusting in Chrome is AdBlock, but don't be surprised if it causes more problems than it solves until there's more consensus on these name-squatters.

AniWeather offers an animated weather pop-up. (Credit: Screenshot by Seth Rosenblatt/CNET)

On that note, there are some excellent Firefox add-ons that have been ported successfully to Chrome. Bookmark synchronizer Xmarks has a beta version for Chrome, as does IE Tab for viewing rendering sites with Internet Explorer's engine within Chrome, and the resource-heavy but still-fun way to view visual media Cooliris.

Facebook for Chrome simplifies Facebook access, putting news feed and status updating in your toolbar. YouTube Downloader grabs Flash video embeds and saves them to your hard drive but interestingly doesn't come from Google itself. AniWeather is another, providing those without windows an excellent way to see what meteorological events are going on outdoors. iMacros will run Greasemonkey scripts and allows users to create their own solutions for repetitive data entry and tasks. The one I can't live without is another name-squatter, AutoCopy. It will copy any text to your clipboard when you highlight it. Unlike the Firefox version, it doesn't open any options when you finish highlighting, so it's a bit hard to tell if it's working as it should.

TooManyTabs cleverly secrets away tabs you want to keep handy but out of your active memory. (Credit: Screenshot by Seth Rosenblatt/CNET)

TooManyTabs isn't TabMixPlus for Chrome, but it does something that TabMixPlus can't because Firefox doesn't yet support it. TooManyTabs manipulates Chrome's tab process isolation in a useful way, so you can move tabs to a holding dock where they're no longer eating memory, but they're still easily accessible. Click on the toolbar button and it opens up a window that displays your active tabs. Arrows next to each one let you move it to the nonfunctional area. A helpful indicator on the toolbar button tells you how many active tabs you've got. Conspicuously missing is drag-and-drop, so hopefully that's coming.

Aviary Screen Capture is another extension that offers Chrome-only features. It lets you take a screenshot of any Web site you're looking at and then automatically opens it in Aviary's image-editing Web suite to streamline your work flow.

The lack of a status bar in Chrome means that the management icons for extensions, if they have them, get added to the navigation bar, something that may annoy users who prefer Firefox's greater level of extension-placement customization. However, it's definitely a more visible placement, and may encourage users to keep their installed extensions to a utilitarian minimum.

More extensions can be downloaded from Google's site or Download.com.

Currently, extension support hasn't been activated in the Chrome for Mac, but that's expected no later than January 2010. There's also some notable popular Firefox extensions that aren't in Chrome yet, such as FoxyTunes. If I've skipped a favorite Chrome extension of yours, or if there's one for Firefox that you're dying to get in Chrome, tell me about it in the comments below.