Tie a helium balloon loosely around his ankle when he's lying down and let him kick and watch it dance about. (onbviously you need to be in the same room as they could get the string)
Wrap something jingly like sleighbells in some bright wrapping paper and let him shake them to death without poking his eye out/banging his gums.
Blow bubbles for him.
Scrub some fruit and veg and let him hold/sniff, maybe even lick them.
Buy an automated swing seat like fisher price takealong swing, they fall asleep in them!
We have a little tykes ocean gym which we use when ds is in his bouncy chair, he loves it, on sale at £15 iirc at asda.
Cbeebies (Yeah, yeah. I know)
Sit him in his carseat next to you when you wash up/cook and give him a wooden spoon to wave, or let him watch the washing going round in the washer. This may make him nod off too.
Read your own books or magazines sneakily by reading them outloud to your baby in an animated silly voice.