It's geared towards designers, and has nothing to do with hourly rates, but I wouldn't want to miss a chance to share this:
F**k You, Pay Me (NSFW language)
I love hourly rates. It gives everybody in the room an incentive to stay focused, and with iPhones, iPads, and laptops in everybody's hands, it's good to have that incentive... I don't even worry about a minimum (a different story, of course, if you are dry-hiring a space that has a minimum). If you charge hours of prep as well, it rewards clients that use reel #s on their clips and collapse to fewer tracks...
I keep very close watch with a pad and paper and triple check the hours are correct before sending an invoice. On longer things I like to send updates to the producer so that they can take issue with your hourly counting right away... and not when they see the final bill.
KC
Prehistoric Digital
PhD Grading Suite