What should I host on my Dedicated Server?

Honestly it's a lot of resources available. As Horizon suggested maybe hosting gaming servers would be something you look into, which is indeed a nice little task and if you like gaming you could potentially join people playing.
You could use it as a storage facility, if you want to dedicate it to the NBB community you could talk with Aoki and come up with a new upgrade or pass that would grant access to the server information, meaning all the leaks and things from here would be there without the need of Unlocking them, you paid for the pass and then you have everything available.

Overall the best and fun thing seem to be the gaming servers and clans, i know it may sound a bit teenager to suggest but there is soo much that you could do that is hard to choose one and gaming would benefit both the community and you in case you decide to have some sort of upgrading systems on there too