A shell extension for Windows (2000/XP) which displays a little lock icon in the bottom left corner of the icon for files which are encrypted with NTFS EFS encryption.
Download the dll (below) and run the following command from your run prompt, replacing the path stuff with the actual path to where you put the dll file:
regsvr32 c:\path\to\dll\statocrypt.dll
Binary: statocrypt.dll
Source: statocrypt_0.8.zip
See license. Contact me when bugs are found.