My cats love boxes. Whiskers is 20 lbs and she thinks that she can sit on top of a box without beaking it. its funny to watch her jump on it and watch her face as she falls through the box.
Abby, my kitten, loves to hide in the boxes and jump out and attack whoever comes near her. Its the funniest thing to watch.

Pros: Cheap fun, all shapes and sizes

Cons: easily breaks

I don't think anything makes our cats happier than playing in boxes. If we leave one sitting the cats will crawl in and roll around, so all you can see is their eyes peering out. They will stay in there for a while, so we have to make sure we do not forget that there are cats in there, so they will not get shut up.

Pros: cheap entertainment for cats, amusing to watch

Cons: clutter up your floor

I always have to check an open box to make sure that the cat isn't in it before I put it away. My cat likes to get in a box to take a nap or just get away from everything. This is one item that most cats seem to like, but just make sure you check the box before you close it up so your cat doesn't get trapped there.

Pros: many different uses, great hiding place

Cons: none

All my life I've used boxes for cat fun. I had fun as a kid cutting "windows" and "Doors" in the boxes for the cats to climb through - then stacking them and setting them side-by-side. What fun the cats had. Now, I set a small shoe box down and my 20 lb. cat tries to squeeze in to it. So funny.

Pros: fun, cheap

Cons: none

every time we get home with groceries, the cats wait for us to put a paper bag on the floor. after we rip off the paper handles, of course! and boxes - they are the perfect place for our cats to put their cherished toys and then play in the box with them!! tons of entertainment for them :-)

Pros: cats seem to love paper products and they cost nothing!

Cons: there are none!