There may be more than one, I just know of one. I am actually thinking about using for my projects as well. It isn't easy though, because you don't get the 20% instantly and not many people want to wait a year to get it. It also comes locked up so you are constantly unlocking rewards.

Being monthly, that means that is the shortest term you can use it for your dApp users without dipping into your own pocket.

In fact, it is likely you will have to dip into your pockets to use the rewards for a dapp which becomes a nightmare in terms of calculating. For example, if you wanted to use HBD to support a weekly reward pool. That's about 0.38% gain weekly if you ignore the 3 day to unlock.