Translate Convert is a great tool for Mac OS X. It combines both a unit converter and a machine translator in a single window.
The unit converter, which you should update from the preferences before using it, has a category drop-down menu, which includes angles, area, currency, density, energy, etc. You type in a value and select a unit, and the app shows you the conversion to other similar units.
Lastly, you have the VAT calculator. Here, you specify a VAT percentage and type in a value and the app gives you a final price.
In short, this is a great app that has three nice features in one. You can access it from your desktop but some of the features require an active Internet connection, like the translator, which connects to Microsoft's translation service.
Pros
- Nice interface
- It can be updated
- Good translation quality
Cons
- None