Command-line. Sysinternals Freeware. Open files from the command line. I really like using the command line.
Occasionally, I'll be in a directory and I'll want to launch the program which is associated with a file (like launch MS-Word to open foo.doc). In Windows Explorer, you just double click and it happens. This is my solution for opening files from the command line. Fiddler HTTP Debugger - Fiddler.