Windows Mobile 6.5: If you're rocking a fairly new Windows Mobile phone, Microsoft offers a beta build of its portable Office applications until April 2010. That means free viewing editing of Excel, Word, Powerpoint, OneNote and other documents.
The app seems to require a touch interface along with the 6.5 system, so it's not exactly meant to flood the mobile masses. Still, for those willing to put up with an occasional bug and goods you know will expire, it's a nice little upgrade. Launch the Marketplace app to grab the Office Beta, or read up on it at the link.
Windows Office Mobile Beta [Windows Marketplace]