I didn't realize this would be so controversial.
My job description is to basically do anything my boss tells me. I do many of her personal errands, etc. She owns the place and I have no problem with that.
The thing that I haven't seen anyone mention is that my time is billable. My boss wants me to bill as much time as possible every day and I am loosing billable hours when I'm doing this associate's personal business.
Also, this associate is actually "of counsel". She doesn't work here full time, yet even when she's not here she calls and has me do personal errands for her.
I think my boss is too nice and won't confront her about it but I also don't think she has any clue the extent of the problem. She's been out of the office in a meeting all afternoon, so I will have to take her my "to do" list tomorrow and see what she says.