We have a ball pit (could do a foam pit as well), trampoline with netting for protection, dome climbing/jungle gym. You can also hang from ceiling swings.
Depending on space...you could do a rock climbing wall, zip line(s), "track" for bicycles
All of the things that we have are geared towards younger/elementary kids. But the rock climbing wall and trampoline may attract older kids too.
We are using some of the money we raised this year to put towards indoor recess items. Our dilemma though is trying to come up with things that will work. We have approximately 150 kids in our gym per recess. What are some things your kids do during indoor recess? Thanks!