I'm a big fan old low tech tools when it comes to meeting and information sharing. There's nothing more informative then a plain white board and nothing more useful then a bunch of sticky notes when trying to plan something.
There are times when these tools are not optimal, usually this happens when all the participants are not physically present. In such cases try using CardMeeting, its a "whiteboard sharing" application that give imitate the behavior of a board and notes just done on a virtual wall that can be seen distributed places.
On the up side the setup is very easy the use is very intuitive and it does keep it very simple. Also, the data can be exported into an excel sheet for future usage.