Gmail, Google's web-based email service, has quietly been adding more add-ons and features via its Gmail Labs. Many of these free add-ons for Gmail - improve personal productivity by embedding widgets on the blank real estate around your inbox.

Gmail Labs reflects Google's belief in agile development and its overall software philosophy: develop new features quickly, release them (even if unpolished) and solicit user feedback. That's quite a different approach as compared to older email systems from IBM (Lotus Notes) or Microsoft (Exchange and Outlook), where changes or additions are large in scale, but rolled out less frequently and in a much more hierarchical manner.

I have a few favourites from Gmail Labs that have helped me cut down on the time I normally take to toggle between applications. Ironically, one of them is even designed to cut down on how much time I spend in email, addressing an endemic problem that plagues the 21st century worker like me.

To add any of these features, click on the green beaker in the top right corner of your Gmail account (just to the right of where your email address appears in bold lettering). Once you're in Gmail Labs, you'll see a list of the add-ons with brief descriptions. You simply click 'enable' or 'disable' for any of these, and make sure you hit 'save' at the bottom of the page. (If more work is required in setting one up, I've noted that in the application info below.). Also, each lab feature has a "send feedback" link where you can write to Google Apps and Gmail developers.

One caveat: as the Google guys and gals like to remind us, this is their test kitchen, so these add-ons could (and probably will) break from time to time.