Mind mapping is also proving to be a popular brainstorming tool. Mind maps employ free association to spin off ideas around a central concept, using a branch-and-leaf structure to clump related ideas together. This reveals relationships and structures as they emerge from the flow of ideas, often leading to new ideas that might not have come up otherwise.
Brought to you by 37signals, the maker of the popular Basecamp project management tool and creator of the open-source Web framework Rails, Writeboard is a free, no-frills, text-only blank space where you can record ideas. Collaboration doesn't come any simpler than this.
Choose a name for your board, select a password, enter an e-mail address, and you're ready to go -- no further registration required. To invite others to view the board or add comments, just enter their e-mail addresses and click the "Send invitation" button.
Writeboard provides few options, but it's great for capturing and fleshing out ideas on the fly. You can type in ideas, move them around and distinguish them with simple text formatting such as headers and numbered lists. Automatic revision-tracking lets you go back and recover anything that might have gotten lost in the shuffle.
HBRLabs' Show Document is a collection of free collaboration tools for Web meetings.
Its Shared Whiteboard app provides a much more feature-rich environment than Writeboard, with an integrated chat room and tools for basic drawing and highlighting. Intended for spontaneous brainstorming, whiteboards created on Show Document are not saved, but users can export them to PDF.
For intensely visual brainstorming, Twiddla offers a full range of drawing tools, as well as the ability to upload images to your whiteboard. Integrated voice chat and media sharing let you add and annotate images, documents or even Web sites while carrying on a conversation.
The basic service is free, while paid professional accounts (starting at $14 per month) allow you to save and share finished whiteboards and use SSL encryption for added security.
Bubbl offers free and simple, but stylish, mind mapping. Mind maps can be started instantly from the home page, and you can register to save your mind maps for future use.