I ran across a blog entry with a consolidated list of links to the SharePoint 2007 planning worksheets. These are good starting points for your discovery, analysis, and design and are provided by Microsoft. I would suggest tweaking them to meet your organizational needs. http://itfootprint.wordpress.com/2007/10/05/sharepoint-planning-worksheets-in-one-place/
TechNet provides a consolidated list of planning worksheets for SharePoint 2010. http://technet.microsoft.com/en-us/library/cc262451.aspx