Exercise equipment and a perch up near the ceiling.

My cats get to hear and see what's going on outside (and if possible
smell it too), they get lots of exercise too. We've used a Skyway
for years, but recently doubled up on the carpeted boards.
Apparently it's beginning to have the effect I was hoping for, that
they would use it for napping and generally hanging out up there (at
least my tame male is). Yea.

http://www.flickr.com/photos/27532210@N04/2975098093/

The boards that lead to the Skyway (see other pictures in my
photostream) are very useful for exercise. Before, my cat would run to
the food bowl every time I got up or turned around. That stopped when
the food was placed up someplace they would have to exercise when
getting to. Nowadays my male runs to the climbing boards and about
halfway up every time I get up or turn around. But instead of worrying
about him getting fat, it's a good time to praise him for getting
exercise.

And that's the good stuff.
Good luck and have fun.