I've never been particularly good at drawing of any kind especially when it comes to diagrams.
So anything that can help my efforts not look like that of a child are welcome which is where SimpleDiagrams comes in. SimpleDiagrams is an easy to use Adobe Air based design application which allows you to draw diagrams far more easily than freehand drawing apps. Note that this is the free version of SimpleDiagrams which has all the functionality of the Full Version but includes a nag screen to upgrade.
Probably one of the most useful aspects of SimpleDiagrams is the ability to draw flow diagrams in order to brainstorm and also plan ideas and projects logically. The interface is ultra slick and clearly laid out allowing you to drag and drop elements into it to assemble ideas quickly. However, to prevent things from looking too clinical, you can also select elements which have a hand-drawn look to give them a more authentic look and feel.
SimpleDiagrams is very easy to use but it's rather limited in formats, saving only to XML and PNG. In addition, there is no way to share ideas and designs quickly by uploading them to a website or sharing server.
If you haven't got the steadiest of hands and you're looking for a free diagram creation tool, you can't go far wrong with SimpleDiagrams.