My former boss (with whom I currently work) has asked me to come troubleshoot a program I wrote about a year ago. I'm scared that i'll go and feel obligated to do hours and hours of work, but I won't feel comfortable charging him for that many hours... but at the same time, I don't want to give up my free time for, well, free.

On an entirely unrelated topic, here's a nice set of FAQs for anyone interested in learning about Multiple Sclerosis.