Excalidraw changed that for me. It's a free, browser-based diagramming tool with a hand-drawn, whiteboard-style aesthetic. It doesn't require you to sign up, no software to install, and the minimal ...

OpenOffice.org's tools for creating diagrams are easy to ignore. For one thing, their controls are extremely small. For another, they are pitifully under-documented in the online help, which plods ...