I am not an inventor but...
1) A foldable tennis racket.
2) inflatable suitcases --- to get a cab quickly --- not advised.
3) Doo-hickeys to put on your thumbs to make it easier to work a Palm "he's all thumbs" was not meant to describe accuracy."
4) Now, will someone figure out a way to work a laptop while eating a meal at a restaurant? It's always so crowded !!!