mamacat, I hope you post here after her next request and tell us that you stood up to her. It sounds like you love your Mom and have a good relationship, but...why are you letting her manipulate you with this? I work in a small office and there was this nice, kind of weird guy who would bring his poetry to the lady who used to have my position. She'd type it up for him, just took maybe 20 minutes. Well, sure enough he came after she left, asking me if I could do the same. Being the nice person I am, I did it. Hmmm...a few weeks later, here he came again.
I finally asked myself, why am I doing this if I don't enjoy it, I don't have the time...and it is my work time, not personal time anyway. So next time he came, I politely told him that I was sorry but I didn't feel comfortable typing them for him. He seemed OK with it and I felt good for speaking up. I urge you to do the same with your mom....As a friend of mine says:
put your foot down but don't let her step on it!!
AuntieJ