A few programs that are good for writers:Freedom
http://macfreedom.com/
A great program that disables your internet for a specific amount of time (active time). The only way to bypass it it is to re-boot, so it keeps you focused and minimises distractions. Free!
Circus Ponies Notebook
http://www.circusponies.com/
A great outlining tool, storing ideas, expanding ideas. Very flexible.
Feel free to add your ideas.
[This message has been edited by skadder (edited April 13, 2010).]