iConvertThat app for iPhone and iPad

iCovertThat has conversion units for:

Length
Area
Computer
Real Estate
Volume
Temperature
Energy
Mechanical Force
Mass
Speed
Flow
Acceleration
Pressure
Torque
Density
Time
Plane Angles
HeatFlow
Electric Current
Voltage
Resistance
Capacitance
Inductance
Luminance

Select the conversion type from the drop down menu, and then select input and output units.

Features:

Units can be swapped from in to out at any time!

Tapping on the action button (White > in circle) will call up an info page on the conversion selected.  Background information and helpful hints on measurement techniques speed up the collection of measurements to be converted, and the pages are educational too!

Allows complete editing of the History pad in portrait mode.  Type directly into the pad, copy and paste to other applications.  All conversions are logged to the history pad with full names of the conversion units.  Excellent for homework or engineering papers.

Has a Real Estate category!