From Traction Software:
Append PDF software automates the process of appending multiple PDF files together, you can append to a new PDF file, an existing PDF file or append a list of files together, the result file is optimized for space. PDF Size optimization is up to 50% better than appending files in Acrobat and using other tools that use Acrobat to append, It also retains bookmark positions to new positions in the output PDF. Optional parameters to only append PDF's with over, under or equal to a certain amount of pages. Now supports .CSV files with list of files to append with. In our tests the appending speed is up to 70 times quicker than acrobat 7 append plus save.