If you been using KDE Desktop there is a cool feature for auto change wallpapers called slideshow, you simply assign folder or many with wallpapers.
But with Wally wallpapers changer there are many features it not only using folders and files to slideshow them, it also can to search for many websites and search engines and fetch pictures to be wallpapers on your desktop such as Flickr, Yahoo!, Panoramio, Pikeo, Ipernity, Photobucket, Buzznet, Picasa, Smugmug, Bing, Google, Vladstudio and deviantART images.
You will get better wallpapers every time when you choose good tag words for searching on those websites.
All wallpapers used can be saved in specific place located by you with each tag for each website.
Download Wally Wallpaper Changer
Download the Last stable release 2.4 From Here.