We use small chunks of putty during long meetings and training...it helps people stay alert, gives them a creative outlet, and generally makes them more engaged throughout.
We also use putty to fiddle around with when we are on long conference calls...boring...until the putty shows up.
For earthquake country, use putty to secure pieces of bric-a-brac to smooth shelves (be careful as it will stick too well to fabric and hair).
Similarly use the putty on the table of a storm tossed ship to secure the plates and cutlery.
Create air pockets and pop them to annoy your cubemates.
Artificially extend your nose. You may have to color the putty to get it to match your skin tone, but most Caucasians can get away with the basic coral color. You can also mimic gross growths nearly everywhere.
Roll into a ball and bounce it.
Create a copy of a pencil drawing by pressing the putty onto the drawing and peel off.
Many folks use silly putty to strengthen their hand muscles and avoid carpal tunnel injury, and some physical therapists recommend it to their patients when recovering from hand surgery.
Pull a big wad apart repeatedly to build up your pectoral muscles (chest area)
Form rings and wear as bracelets and necklaces. Nice if the putty is colored and large jewels are embedded. The height of gooey fashion.
If you make a sort of paddle shape with it and slap a table, it makes a loud bang. IF you do it right.