There are thousands of Google gadgets you can add to your iGoogle pages, from email checkers, games, even (wow, over 70) Twitter clients. The framework for these gadgets is flexible, allowing most of them to work not only in iGoogle but also on your PC using Google Desktop and in Gmail as a labs plugin. So when we write about a particular gadget, although it may not get as big as an iPhone app, there's still a lot of potential there.

The Google gadget called What's Popular came to our attention thanks to Steve Rubel's blog Micro Persusion. His take is that it has the potential to rival Digg. While we think that might be a bit ambitious, we definitely think the gadget is a lot of fun.

Using the What's Popular gadget is simple. Just visit its gallery page, click on the 'add' button and you are done. Once you visit your iGoogle page, you'll find it running and already bristling with popular stories and links. By default, What's Popular finds trending content on Google sites like News, YouTube, and Reader. You can also submit links to it for consideration.

Voting on stories is just as easily. Pagination is automatic, so you just scroll down the list, clicking on stories you want to read and voting stuff up or down as you please. More stories appear as you scroll so there's effectively no bottom. The widget keeps track of all the items you voted on (making voting another form of bookmarking) and also all the URLs you submitted along with how popular they have become. If you maximize the widget, more options are revealed, like the ability to sort by story, image or video, and by date or popularity.

That's about it. Quick to load, endless supply of interesting links, ability to vote - ok, it does sound a little like Digg. However, there's a key component missing: commentary. Your opinion can only be made with your vote (and, I guess, the 'report abuse' button). There's no way of providing any additional web resources, opinions, or, well, anything. Plus, it's hard for us to see how a widget that is competing for screen real-estate with a stock ticker and a twitter client will take down a community site like Digg.

StumbleUpon, on the other hand, may want to watch this one carefully.