Apple iWork Suite (free)
Pages allows you to import Word documents and export to PDF and ePub.
Pages is the most beautiful word processor you’ve ever seen on a mobile device. This powerful word processor helps you create gorgeous reports, CVs and documents in minutes. Pages has been designed exclusively for the iPad, iPhone and iPod touch with support for Multi-Touch gestures and Smart Zoom.
Keynote allows you to import Powerpoint documents.
Keynote is the most powerful presentation app ever designed for a mobile device. Built from the ground up for iPad, iPhone and iPod touch, it makes creating a world-class presentation — complete with animated charts and transitions —
as simple as touching and tapping.
Numbers (for those needing spreadsheets)
Numbers allows you to import Excel documents.
Numbers is the most innovative spreadsheet app ever designed for a mobile device. Created exclusively for iPad, iPhone and iPod touch, Numbers includes support for Multi-Touch gestures and Smart Zoom so you can create powerful spreadsheets using just your fingers.
Dropbox lets you bring all your photos, docs, and videos anywhere and share them easily. Access any file you save to your Dropbox from all your computers, iPhone, iPad, and the web. With Dropbox you’ll always have your important work with you.