Sprout, the company that makes it easy to build interactive multimedia widgets in the Flash format, is now letting companies customize its widget maker for marketing campaigns. You’re probably thinking, “Pfft, marketing widgets, what’s special about that?” But Sprout’s FanKits — starting with a kit for the upcoming Sony movie Nick & Norah’s Infinite Playlist — are interesting because they’re essentially a branded and customizable version of the Sprout platform, allowing fans to build the widgets, and to further customize them whenever they’re shared.

San Francisco- and Honolulu-based Sprout has been getting a bunch of great reviews because its tool makes it ridiculously easy to create top-notch widgets through a WYSIWYG (“what you see is what you get”) graphical interface that’s similar to Photoshop.

With the Nick & Norah kit, for example, users can build a widget with pages of videos, pictures and music (from music site imeem) that you choose. And it’s not just the limited selection provided by Sony, but pretty much any media you can find online and want to use  — Sprout chief executive Carnet Williams says FanKits can be “as open or as closed as a company wants.” Even better, when another user sees one of the promotional widgets, not only can they embed it like a normal widget, they can also “remix” it — basically using the existing widget as a template to build a new one.

There are tons of widget advertising companies already out there, and some of them have pretty similar offerings. But I don’t think Sprout is trying to compete directly with Clearspring, an ad network that uses widgets — in fact Sprout works with Clearspring and other networks to distribute its widgets). It’s just trying to provide the tools for making widgets, and to create different products to make money from those tools. FanKits are a good first step.

Here’s a widget that the company made promoting the Sony deal and FanKits in general.

http://farm.nickandnorah.sproutbuilder.com/load/LAAxDwpNAFzQck5L.swf

Sprout has raised about $8.3 million venture backing.