The following link describes bit assets best:
https://bitshares.org/technology/price-stable-cryptocurrencies/

Look at the "Introducing SmartCoins" and "the Long (BitUSD holder)" sections.
You can typically sell your BitUSD on the open market for about a dollar or slightly above. If liquidity is poor you can force settle for $1.00 and this will take an hour or less to perform.

There are several bit Assets that offer returns.