PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
PDFTK Builder - PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use.
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat
7-PDF Split & Merge - Functions: Split pdf-files, Merge pdf-files together
Ultra PDF Merger - Ultra PDF Merger is a freeware PDF utility that joins your PDF files, or part of them, together.