Available from: http://robotronic.de/runasspcEn.html and free for home use, this little utility is awsome.
It allows you to run programs as another user, without having to type in their credentials and, most importantly, without their credentials being in plain site.
It does this by creating an encrypted file, which contains details about the app to run as well as the user credentials. When invoked and pointed towards this file, the app runs with the previously encrypted details.
The app also verifies the app being called is the one you intended by the use of a hash compare – this means that somebody can’t simply, for example, rename cmd.exe and have that run instead.