With this plugin for windows explorer you can see thumbnail of maya scene files if they have swatch files.
(if no swatch files you can grab swatch from renderview.or a better solution I wrote a small script that generates
with the plugin also you can see IFF and XPM thumbnails.
I can add some more like SGI,RLA,RGB etc. but depends requests. iff is enough for me
this small video obviously explains
http://www.ddmel.com/miscfiles/mayapreviewer.wmv
for more details,take a look into help file.
INSTALLATION
1-put mel in scripts directory.
2-put each 3 file in windowssystem32 directory
3-execute batch file regxpm.bat;
UNINSTALLATION
1-execute batch file unregxpm.bat;
2-then delete each 3 file in system32 file manually.
ScreenShots

