We met an old friend today

Look who turned up on our doorstep! Boys loved it! Sadly Greg is not staying in our house but is off to a school. Sadly not my school either, but I did suggest to owner Greg could school hop!
I have been stocktaking my school library and Diary of a Wimpy Kid books have grown legs and run away ...
An alarming number of them!
I think this is THE book ( or series!) for this generation , just like the Harry Potter sensation years ago. (those sit on my shelves and never go out! Far too thick for my students I think.)

What books do you think define current kid's lives?