At 14.1", this is one of the largest digital photo frames on the market. It's from Westinghouse, and can display multiple photos at the same time with its MosaicView technology. The technology also allows you to set up an entire slideshow, and provides support for JPEG, AVI Motion JPEG, and MPEG-1 and -4 files. The slideshow function comes with with a variety of transitions, variable speed settings, or regular, "plain" picture viewing.
The 14.1" size in Westinghouse's line also sports 16:9 aspect ratio--and if these functions aren't enough, the best is its most basic feature: 1200x800 resolution, as good as many computer screens. Multiple USB ports and SD ports make it likely that it's compatible for transfers directly from your digital camera to the frame. It's available through Amazon dealer Electronics Expo for $100 off the MSRP of $399, making it only $299 to get a top of the line digital photo frame.