I agree with the getting more rats option, I can't get enough of my girls and boys and let me tell you, between them, the dog, the cats, the guineas, the bird and the hamster... I'm plenty busy enough lol.
There was a thread made just a few days ago that gave some great ideas of games you can play with them. Here's some ideas from that post and my own to set up a fun free range play area:
-Free ranging toys - such as ferret toys, jingle balls, etc
-Pea fishing containers
-Digging box with sand or dirt
-A pile of towels to let them rummage through
-Pieces of paper that are made into "tents" to crawl under
-Gnawable toys such as wooden sticks, etc.
-Hidden yogis throughout their area
-Teach them to fetch a ball
Also, you could set up one of those training areas for when people train rats to do tricks.
Two boxes with a tightrope (ladder) between them, ramps, hoops to jump through, etc.
If THIS isn't enough for you, I don't know what will be