PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
jPdf Tweak - jPDF Tweak is a Swiss Army Knife GUI application for PDF documents: combine, split, rotate, reorder...
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
PDF Arranger - Small python-gtk application, which helps the user to merge or split pdf documents and rotate, crop...
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat
PDFTK Builder - PDFTK Builder is a free graphical interface to for PDFTK, making it much easier to use.