Does your mother put guilt trips on you for things? If so, how do you deal with that? If not, how did you get her to stop?
No, thankfully my Mom's not that kind of Mom. Occasionally she'll do the "I'm a bad mother!" bit but I think every mother does that. She doesn't guilt trip me for stuff. Though she has been known to hold me accountable & challenge me when I'm not acting like a person should.
I read a really good book a couple years ago about boundaries -- it was honestly one of the most useful things I've learned as an adult. It's from a religious viewpoint but helped me IMMENSELY in dealing with every sort of issue from a secular standpoint: http://www.amazon.com/Boundaries-When-Take-Control-Your/dp/0310247454. If there's a secular equivalent I'd love a link to that as well, or an article summarizing the main points of the book -- it's very useful stuff and I refer to it more than almost any book on living life (except for Hitchhiker's Guide, of course).
Also high on my list of Most Useful Book Ever would be this one, pertinent to all relationships, not just marriages, and useful for me in relating to my family: http://www.amazon.com/Seven-Principles-Making-Marriage-Work/dp/0609805797. (But then I'm divorced so my credibility is only so-so.)