I've been playing around with this iPad add called, 'RetirePlan'. Pretty nice, I would recommend it. I have yet to find a site what does what the app does.
I really like how this app lets you tweak all sorts of inputs and play around with different scenarios. One thing that they need to fix tho, is... the email to functions doesn't work.
Oops, yes, I should have mentioned it's $5. My bad.
I read a review of this app saying it uses average returns as the basis for its calculations. If that's the case what does it do that all the free average return calculators don't do?