I see there are simulations of most of the HP Voyager series calculators on the App Store -- the 11C, 12C, 15C, and 16C. I loved these calculators in their physical form. I still have my original 12C that I bought in 1982 when I started my MBA. I'm tempted to buy the 15C for the iPhone if it is a good simulation with good "key" response. But at $19.99, I'll wait for a few more reviews just to make sure it's superbly done. I already have R.L.M.'s 12C, but that was a lot cheaper. Now I'm just waiting for some mega-dork to simulate the iPhone on an HP 50g.