You can start by using a questionnaire like this one to figure out what percentage of your portfolio should be in bonds based on how long the money will be invested and your comfort with risk.

FORBES: Is the Rising Bond Market Your Friend or Foe?

What ZestCash aims to do is really look at that question of risk propensity, using an online questionnaire and a risk manager to determine, in a Google-like data crunching way, just how risky this prospect actually is.

FORBES: Google-Style Money for America's Poor