OmniGraffle

The premier diagramming application for Mac OS X

Allows for running Windows on a Mac system

A free office suite that includes a word processor, spreadsheet software, and a number of other useful tools

Free and simple organizational desktop tool for productivity available for Mac OS X

A drafting tool that's specialized towards professional needs like diagramming, illustrating and flowcharting for businesses

Create maps to sort out problems and issues

Time-tracking and invoicing tool for work