Blatantly not an AIBU, I know you lot come here more than anywhere else 
I am so, so, so, so, so fed up of the " but you didn't tell me you were going out", "I didn't know she doesn't have karate today!!", "I told you 3 months ago I had a work trip next week" arguments.
We have:
- my paper diary which is the master diary. It sits on my desk at home 24/7, and contains everything I need to do, the kids need to do, family holidays, memorable things DH needs to do (hardly anything), plus everything he tells me (which isn't everything, and never any amendments)
- month-to-a-page calendar on the fridge: kids' extra-curricular stuff, days off school, birthday parties, other birthdays to note, family holidays, and when he remembers to put them there DH's work trips (but he'll sneak them on and not tell me he's updated it). Neither of us look at this every day
- DH's work diary, which is chockablock every day, changes every day, and contains last minute travel stuff (he goes somewhere at least once every 3 weeks, for a day to a week at a time)
- we text all bloody day about plans for that day and next week and next month. I put what I can in my master diary, but stuff changes and then we have the "but I sent you a text on Wednesday telling you it had changed" discussion
WE. CAN'T. STOP. ARGUING.
We've tried a shared online diary: it doesn't synch with his work because of IT security.
He's tried to make his work travel arrangements come to my email automatically: I refuse to be his PA, I've got enough on my plate as it is, all he needs to do is tell me shit
We've tried using just my diary: he can't read my writing, I can't read his
We've tried using the fridge calendar for everything: it's too fucking small to fit everything on, and anything big enough would frankly need to be bigger than the fridge.
I don't want to a great big bloody white board up on the wall, it would ruin the aesthetic of my home 
HELLLLLLPPPPPPP UUUUUUSSSSS!!!!