We have an indoor bouncy house for our daughter. It's great fun, especially when other kids come to play. Plus, it literally pays for itself in babysitting fees because several couples can enjoy dinner and talk about boring adult stuff while the kids entertain themselves in the bouncy house (and then immediately fall asleep exhausted at the end of the evening).
Our specific model is a Island Hopper Jump-A-Lot Double Slide Bounce House 2012 available from Amazon here
. I've been very happy with it, except that the walls along the top slide aren't high enough, and I fear someone running down the slide (as 3-year-olds are wont to do) might fall out. To help prevent this, I sewed on webbing loops and installed a rope safety net, effectively extending the wall upwards.