Documents by Readdle - A central hub for all your files.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
Documents Pro 7 - The ultimate all-in-one mobile office suite for the iPhone and iPad with 8 premium apps in 1.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
GoodReader - With GoodReader on your iPhone, iPod Touch or iPad, you can read virtually anything, anywhere.
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat