There’s been a lot of discussion around about the .jpg file downloaded to iChat that was in fact a trojan in the form of a Unix executable with it’s extension and icon changed. This little script catches such files if you run the script against the file but don’t double-click the file you suspect. It could also be used as a folder action on a download folder (with the appropriate handler script added)
set theFile to choose file
tell application "Finder" to set suspect to (get info for theFile)'s kind
if suspect is in {"Unix Executable File", "Terminal.app Document"} then tell application "TextEdit" to open theFile
display dialog suspect