Bonus Chips (BC) don't have a cash out value but they do have uses.
At Poqery you can use them to highlight your answers or questions giving them a better chance of being seen or answered. Also when you highlight a question 50% of the BC you use will become the reward for the best answer. This incentivises the best players to write an answer to your all consuming question.
Bonus chips can also be used at NoPayPOKER to give you an advantage in Freerolls, where the BC you add to a Freeroll builds up your starting stack. Right now you cannot transfer from Poqery to NoPayPOKER but that may happen at some point in the future.