Oh wow. Here are some tetris blocks I made recently.
And here's another one.
They were made entirely from single crochet (US terms) with a 3.5mm hook and some random 8-ply from my stash. I'm currently in the process of making the line, square and L blocks.
I think these would be a good, quick (A day each block), simple (I'm sure you can work out a pattern just by looking at them) present for a babby.
I brought them to uni and they spent half the day being cuddled by geeks.