-- Before our wedding, my then-fiance, myself, my parents and my MIL had all agreed that there would be just two speeches - my father and my husband. My MIL was (apparently) not happy with this but went along with what everyone wanted.
At another family event, a couple of weeks before the wedding, her brother spoke. My MIL pipes up: "Oh, that was beautiful! You'll have to speak at the wedding, What do you say, [Mizza76]?"
Luckily I had the guts to say no and didn't mind at all looking like the mean one in front of my new family, who didn't know about our arrangement...
-- A few weeks before I gave birth to DD1: "Oh, do you need me at the birth? I'm planning to go on holiday but will stay if you really want me to"
-- At a meal with a cousin visiting from abroad: "Why don't you come to dinner at my house on Tuesday at 6:30 - you can go to [mizza76] and [DH]'s first, say at 5:30, for drinks"
I had already asked her several times not to invite people to my house without asking me first (as she had already done this several times), but apparently this was unreasonable.
-- "I really need you to call me, it's an emergency" - message she left on my husband's mobile several times one day while we were on holiday. When we couldn't get through to her we completely panicked, called his siblings overseas, considered coming home early... Turns out she couldn't work out how to use her fax machine.
-- Too many others to count.... Other favourite incidents include her giving me a book she had bought for herself at an airport and read on a plane as a birthday present, and not visiting or helping out at all after I had a miscarriage (and lived less than 5 minutes walk from her).