Some clever airlines are now adding separate drop-down cup holders into their seat-backs (love you, Emirates!) but many of us still find ourselves having to pull down the whole tray table just for somewhere to keep our coffee or Coke. Step forward the Airhook (£21) which clips onto a stowed tray table to hold a drink, and also provides you with a place to secure your phone or tablet if there's no entertainment system. It's simple, but game-changing!