Tapbots has Calcbot — Calculate Intelligently (iTunes Link) in the iTunes App Store for 99-cents for a limited time.

Calcbot is a simple and beautifully designed calculator for your iPhone, iPod touch and iPad.

Never lose your place in a calculation again with the live as-you-type expression view. Simply swipe the keypad to the left to reveal advanced functions. See your past calculations in the history tape. You can even send old values and expressions back to your calculator or to a friend via email.