.....you know, the ones you thought would happen on a regular basis pre-children and which you now find are instead as rare as hen's teeth!
Today DS2 (7yo) said, off-handedly, "Mummy, do you know Shakespeare?" I said "Why yes darling. of course!" in delight (I am a massive English literature geek). Unbelievably, the conversation ended up with us sitting on the sofa watching the Cbeebies re-enactment of The Tempest (watch it on iPlayer, it's good!) with my copy of Shakespeare's complete works in front of us, quoting lines as we came across them. It was utterly wonderful. I am absolutely certain that nothing like it will ever happen again and that's my lot, parenting joy-wise 
Please tell me your best moments :)