My own cuddle monster is in the middle of six weeks cage rest with a broken leg, so we've been all about the enrichment.

So far the biggest hits have been:

Putting her dog food in a Kong and freezing it.
Treats in an empty plastic bottle, and then when she got the hang of that putting the bottle inside an old sock.
Hiding her kibble around the room so she has to sniff it out.
Tricks wise, in the last three weeks I've taught her high-five, play dead, and half of roll over.