I've been asked by various people what I use to create the diagrams and illustrations in my blog here. I am using SmartDraw. It makes it easy for people like me (who know what they want to show but lack graphical talent) to create stunning resonably good looking business graphics. Have a look at some samples, their tutorials or follow their blog. My only grieviance is, that they don't have a Mac or native Linux version (and it doesn't work with Wine either). The other graphical tools I use regularily are Shutter for screenshots and Buzan's iMindMap for mindmaps. While SmartDraw does mindmaps too, iMindMap draws that wonderful organic connectors - and runs on Mac/Linux too. Occasionaly I also use Dia, Inkscape or Gimp.