I loved post-it notes so much as a kid that I begged for (and got) Doctor Barbie just because she came with a pad of mini post-it notes!
It's not just sharpies and post-its though. I have a deep affection for all things school/office supply related! I love little notebooks, stationary (though I don't write many letters anymore), stickers (did I mention I am 29 going on 8?), and I keep a paper calendar that update with colourful papermate flare pens - they write like ultra fine sharpies without bleeding through!
Here's the proof: