Reviewing my system, I realized one script I take advantage of the most is a logging script I made years ago to track logins.
I mainly use it to see who is using which computer, saving on guesswork and coming in very handy when troubleshooting weird problems. It also comes in handy when tracking down an asset or debugging login issues (i.e. if there's no connection during login, it won't write to the logfile.)
So here you go, in all its VBScript glory: https://gist.github.com/zyphlar/1793697