If you don’t mind “beta” software, are a Windows 7 user, and you convert your camera’s RAW files to the Adobe DNG format, then this “release candidate” DNG Codec is for you.
According to Adobe:
The DNG Codec provides a method for Windows 7 customers to view DNG files in the Windows Explorer and Photo Gallery.
The biggest downside, in my opinion, is that it doesn’t offer support for OSes prior to Windows 7. Then again this is 2011; I suppose we should all be on the latest and greatest OS, unless you count this one.