U.K.-based Byte Squared sells the Office² productivity suite (word processor, spreadsheet, slide viewer, etc.) for the iPhone and iPad, as well as individual apps from the suite. The iPad suite has a rating of 3/5 stars in the App Store.
Byte Squared made limited traction competing against the likes of Google (owner of Quickoffice) and Dataviz (creator of the Documents to Go suite). Also, Microsoft recently launched Office apps for the iPhone and Android.