Documents by Readdle - A central hub for all your files.
DocuPUB - DocuPUB is an online file converter, file merger, file compressor, and file resizing tool.
Documents Pro 7 - The ultimate all-in-one mobile office suite for the iPhone and iPad with 8 premium apps in 1.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
GoodReader - With GoodReader on your iPhone, iPod Touch or iPad, you can read virtually anything, anywhere.
7-PDF Split & Merge - Functions: Split pdf-files, Merge pdf-files together