Many software downloads will supply an 'SHA1 Checksum' to verify that what you downloaded is what the developer intended and not some malware pretender. It may not be obvious how to check this without using Terminal.
I created an Applescript droplet for verifying the 'NSA Secure Hash Algorithm 1' checksum that is sometimes supplied to authenticate a download. It's pretty simple, calling a shell script to output the checksum hash.
Just paste the following into AppleScript Editor and save the script as an Application.
-- if applet is double-clicked
set chosenFile to choose file with prompt "Select the file to checksum:"
do shell script "/usr/bin/openssl sha1 " & quoted form of POSIX path of chosenFile
display dialog result buttons {"OK"} default button "OK"
-- or if the file is drag and dropped
on open chosenFile
do shell script "/usr/bin/openssl sha1" & quoted form of POSIX path of chosenFile
display dialog result buttons {"OK"} default button "OK"
end open
Mac OS X Hints
http://hints.macworld.com/article.php?story=2010060915020592