Sprout, which offers an interface that companies can use to build interactive marketing widgets, is broadening its platform today with a new feature called the Sprout Mixer. The new feature lets client companies give their fans the chance to build widgets for them.

When Sprout launched at the DEMO conference in early 2008, it attracted a lot of positive buzz for its Sprout Builder, which was a Photoshop-like interface for building widgets. These widgets were much more interactive than your average marketing widget, which usually offers just a few interactions; they were more like fully fledged websites distributed as widgets, which is why the San Francisco company tried to differentiate them by calling them “sprouts.” Then the company launched FanKits, which were basically a branded, customizable version of the Sprout platform. Launch partner Sony used FanKits to promote its film Nick and Norah’s Infinite Playlist by letting users build their own Nick and Norah widgets, including, of course, a playlist (powered by music site imeem).

With the Sprout Mixer, anyone can follow in Sony’s footsteps — rather than working out a partnership with Sprout, you can just sign up, then use an interface similar to the Sprout Builder to make your own version of Sony’s FanKit. In other words, you’re building your own branded widget builder.

Chief executive Carnet Williams says the Sony campaign was a success, although he can’t release any numbers. Sprout is also announcing a partnership that will integrate Google Analytics with Sprout Mixer so that clients can track the success of their own campaigns in more detail than they could with widget networks like Gigya and ClearSpring, which Sprout has already partnered with. (Gigya and Clearspring could be seen as competitors too, but they’re not offering anything the Sprout Mixer. Another competitor called Flypaper, which also launched at DEMO, is now focused on sales and marketing presentations.)

Of course, I had to ask Williams how Sprout will be affected by the economic downturn and the drop in ad budgets that will almost certainly follow. Williams pointed out that Sprout Mixer still offers a lot of bang for your buck, because of the high level of engagement — users aren’t just looking at an ad, they’re not even interacting in a cursory fashion as with most widgets, they’re actually building the ads themselves. And it doesn’t cost any more than a normal ad using the cost-per-click model.

I also asked him whether Sprout had gotten much use during the recent election. Some local politicians did use Sprout to build some sophisticated campaign widgets, and Williams said he’s hoping to see usage really take off in the next election. After all, widgets are a good way to reach potential voters who might not visit your website.

“You can take your content to where the users are,” he said.

You can see a demo video of Sprout Mixer behind the jump. Warning: It starts playing automatically.

http://farm.sproutbuilder.com/load/YwDGgWB_DjMOvc7O.swf