
Any suggestions on policies in terms of encouraging employees to take good care of their hardware, ranging from charging them for lost, broken or stolen company goods to rewarding well-maintained hardware or reduced helpdesk tickets?
Apple's recently been accused of voiding warranties for cigarette smoke, and I'm curious if any other IT departments have gone that far. 



I think you should develop a disposition report for any piece of equipment issued. Using this form you would be able to collect the equipment from employees who were leaving and be able to document the condition of each piece upon collection and reissue. This would allow for the company to adequately account for equipment which becomes antiquated, broken through daily use, or even hold the user accountable for improper use.
This is the method we used when I was a telecommunications installer and seemed to keep people on point without victimizing employees.
I agree with the other guys – tell employees it’s their responsibility, have them sign off/out the equipment, and hold them accountable if necessary.