Ironically, you can now use Office Web Apps -- Word, Excel, PowerPoint, and OneNote 2013 -- on iOS devices, as long as you start with Google Chrome; see the article link below for more details. The Office Web Apps 2013 beta also works on the Nexus 7, if you follow the same steps (request the full SkyDrive site/page). See this Office Next post for more details on the new Office Web Apps.
"Even though Microsoft does not yet officially support the iPad on its Office Web Apps, you can still access the online productivity suite thanks to Google’s recently released Chrome browser for iOS. It’s not a perfect solution, but if you need to get some editing done in a pinch it’ll work."Edit Docs on Your iPad Using Microsoft Office Web Apps | PCWorld