I have a variable request, but it may be a bit too maker specific... On Nikon cameras, when used with a VR lens, information is written in the maker notes which tells you whether the VR is on or off. I am fairly certain its in the Makernotes portion of the exif data. Anyway, it would be nice to be able to have this available as a variable.
I will say up front that I really don't know how much Nikon's own software uses this. I know that ViewNX and CaptureNX have a field for it in the metadata, but it doesn't work with my Nikon bodies (D50 and D200). Nikon has responded that its not supported on those. *However* using the Exiftool program, I have verified that the D50 and D200 *DO* write this info.
Anyway, I realize this may be a "niche" request, but others may find it useful as well...
PS I don't know if Canon has something similar...