I've gotten in the habit of counting how much time I have left at work by figuring about how many songs have to play on the radio before it's time to go. I estimate 3 minutes as song, and commercial breaks count as "songs". It's fun because I'll figure it out and then write down the number, then sit there marking tally marks for each song, and I doubt the boss man really knows what I'm doing.
Right now there's about 57 songs left before I can go home. HOOOOOOOOOOME.