Freefileviewer - Free viewer for PDF, DOC, DOCX, PHP, CFG, DAT etc. files
Documents by Readdle - A central hub for all your files.
Ubiquitous Player - Portable music player, image viewer, file manager, and more.
GoodReader - With GoodReader on your iPhone, iPod Touch or iPad, you can read virtually anything, anywhere.
FE File Explorer - The one-stop files solution
DiskInternals Linux Reader - A freeware tool for extracting files from Ext2/Ext3/Ext4, hfs and ReiserFS partitions in Windows