Michael Dunn developed an interesting Gadget for Browsing the Astronomy Picture of the Day.
However, using the original version published on CodeProject, I failed to install the gadget on Windows 7 x64. (Browsing the comment section, it seems I was not alone.)
Fortunately, source code is available in the download package. The gadget uses an helper COM object, written in C++ with good old VC6. I imported the C++ project in VS2008 and rebuilt for x64 (in fact, to my knowledge, it is impossible to do 64-bit builds using VC6). After repackaging the gadget with the 64-bit COM object, the APOD viewer correctly shows up in Windows 7 x64.
The x64 build is attached to this post.