I feed a stream of crypto prices onto the Ethereum block chain. Anytime you exchange crypto for Unum, it looks up the USD equivalent and issues the corresponding # of Unum.

I think the two main points that make Unum different is 1) it's decentralized, so you don't have to trust me or some shady organization,  and 2) it's simple.  Biteur and bitusd are...complicated.