Posted for Micah Froese <micah@froese.com>:

 
 Couple of points on opening unknown files....
 
 1.  If you don't know the source, don't open them.
 
 2.  Look at the file size, there are often small files that a program will
store somewhere as a reference for itself; if you're looking for, let's say a
picture, a 1 KB file won't be what you're looking for.
 
 3.  I often open files with unknown extensions in Microsoft Notepad, it opens
almost anything and at least gives me an idea of what it is.
 
 Micah