ms word would come in handy as an app since most businesses(at least the people i work with) still use that for docs. it would just be nifty to be able to edit docs when you're caught away from your computer.
There are several apps on the AppStore that let you edit .doc and others. They are: QuickOffice, MobileStudio, and Documents?maybe, haven't checked?. For Cydia there is iFile.