A new site, due to launch soon, called Wesaturate, plans to offer RAW files for people to download, so that one can practice raw editing if you don't have access to a camera that shoots RAW, or alternatively, I presume it will be useful for trying raw files from specific cameras (if it will let you search for specific cameras).
According to Dp Review:
Wesaturate is tentatively scheduled for a full launch on April 17, though at the moment it is only accepting email addresses from those who want to be notified about the launch. A single image is currently offered on the site in both Raw and JPEG formats; it, and others uploaded later on, are offered with a Creative Commons Zero license. Once the site fully launches, users will be able to share their own photos with the Wesaturate community.
Via Dp Review