Fidelity.com: Fidelity myPlan℠ Snapshot
It's pretty easy to fill out, requiring only five inputs — and those inputs ought to be easily available to just about anyone with a shadow. (How old are you? How much do you make per year? How much have you saved so far? How much are you saving monthly? What's your investment style?)
Once you get to the final summary screen, you can then tweak your numbers to see what effect the changes would have. Pretty neat stuff.