There are plenty of wallpaper-changing applications out there, and plenty of them can tap into photo sharing sites like Flickr and Photobucket for access to a plethora of images. Still, not many of them are quite as well-connected as Wally.

Even fewer are cross-platform. Wally, though, is happy to share its background-rotating skills with Windows, Mac, and Linux users alike. It’s built using Nokia’s Qt4 framework and supports an insane number of image sources: local and remote folders (via FTP), and popular photo sites like Flickr, Yahoo!, Panoramio, Pikeo, Ipernity, Photobucket, Buzznet, Picasa, Smugmug, and Bing. You can use any combination of sources you choose by adding and removing them on the settings screen.

Customization options are plentiful, from specifying the delay between image changes to tweaking the size of your local image history store. Images from the ‘net are pulled in based on the search terms you specify – and yes, you can shut off Bing’s adult filter if you want to.

Wally is free and open source, and pre-compiled downloads are available for Windows, Mac, and Linux. The project is also mirrorerd over at Sourceforge.