It is really interesting seeing all the different way people use their ereaders isn't it, and you can see logic in pretty much all of them. Not sure about DiapDealer's practise of only buying books when ready to read them though - like pidgeon92 I have a wishlist and more often than not buy my ebooks when they are on offer. If I waited until I was going to read them, think of the bargains I might miss out on!
As for Mum's reading, since getting her Kindle my Mum has never read so much in her life, I think she would be completely lost without it now. I've tried to show her how to use Calibre but I end up having to load the books onto it for her, but she is happy enough using her PC to buy them on Amazon and get them delivered via wi-fi.