Marco Torretta has Amount (iTunes Link) for the iPhone and iPod Touch in the iTunes App Store for FREE (regularly 99-cents) for a limited time.

Amount is the most intuitive, lightweight and easy to use unit converter you’ve ever seen.

Amount let you convert units in a way you’ve never seen before: with just two tap of your finger you have all the results you’re looking for in a single display, side by side.

When you use Amount you don’t have to think what a number is and choose from a long list of values which unit assign to it, spending time. Just let it do all the stuff!