PDF editor, free, for Windows for rotating PDFs - PDFTK Builder

PDFTK Builder is a nice free software with a good GUI in case you need to do minor changes to a PDF file such as rotating a PDF scan (my case).

Edit: This is also great for splitting and merging pdfs!

http://angusj.com/pdftkb/#pdftkbuilder

Full installation (includes PDFTK ver 1.41): 2 MB
http://angusj.com/pdftkb/pdftkb_setup.exe