I second the cubby idea! Cubbies can then relate to other play such as caves to hide in, boats to sail in, buses to ride in.

If your DS likes transport and understands about using tickets on the bus/train etc, you can set up a few chairs to make a bus/train and get him to use a 'ticket'. He can take his teddies on board and get them on and off and different 'stops' etc...

What about a sorting game? My DD loves sorting and posting. I have cut out pics from photos and magazines and then cut a slit in a box. She can spend hours naming the pictures and then posting them in the slot.

Baking is def a good idea... getting kids involved in food is great if a little messy.

Don't forget it is a really good idea to allow kids to expend a bit of energy every now and again as it helps them to settle and focus afterward. We sometimes worry that it will set them off, but it should in fact do the opposite. If you can manage it, have a bit of a dance/sing, active simon says etc just before you LO's nap time to get all of that energy out!

Finally, how about googling something like "activities inside two year old"? The internet is your best friend when it comes to this!