I was recently looking into "brainstorming" or idea linking software, and I tried about 20 different open source products. I even tried visio with some brainstorming templates.
Not what I was looking for.
In the end, the CLEAR winner, for me and my particular idea diagramming needs, I ended up sticking to yED - which is FREE.
Why I like yED over all the others? It doesn't auto place the nodes! every other piece of software for diagramming has only specific places nodes can be placed. yED doesn't care. And the best of all, you can import your own transparent PNG files for your own custom icons.
It costs a few hundred bux less than visio, and I think it's just as good for 99% of what you are going to do.
