CS6 PDFs are all available for download from this obscure URL
While the links to all PDFs are on an Adobe blog, individal links to Help PDFs are available two ways online:
On Adobe.com: Each product's Help center has links to the PDFs in the Help & Tutorials section of the page. You can access all Creative Suite product centers here:
From the Help menu in each product: select Help to go to the Help & Tutorials page. There's a link to the PDF in the What's New section of the page.
For example, see InDesign Help & Tutorials here: http://helpx.adobe.com/indesign.html
Community Help & Learning team
Europe, Middle East and Africa