DS is a tiny bit older (nearly 18 months), but here are some of the things we like to do:
A towel on the kitchen floor and a washing up bowl full of warm water and bubbles can keep him happy for half an hour. Then 10 minutes of drying everyone off and changing clothes.
I recently discovered cloud sand (I think that's what it's called, can't remember exactly) which is basically 1 part baby oil and 5 parts flour. I used wholemeal for added texture, you can also add in glitter if you want. Mix it together and it turns sort of, umm, sandy - you can mould it to make mini sandcastles with egg cups etc. Anyway, we play with that on a tray, and use saucepans, dry pasta, DS's toy dumpertruck, spoons, etc etc. Again, 20-30 minutes entertainment, plus another 10 while DS 'helps' me sweep it all up and vacuum.
We spent 20 minutes yesterday playing with the contents of my button box. He enjoyed examining the different buttons, and moving them from the box to a tray and in and out of little containers. I put it all away at the first sign of one going in his mouth or being thrown.
I got a sticker book for £3.99 the other day and it has already provided hours of entertainment.
All of the above are safe because there is an adult playing too, I wouldn't leave him to do any of them unsupervised.
Cars, balls and books are also favourites, and he has just (this week?) got interested in colouring ('drawdraw'!) but has yet to grasp the concept of keeping it on the paper and not the floor/walls/chair.
I can't wait until the summer comes and we can spend more time outside, DS's idea of heaven is a puddle and a stick 