Is there still not a reasonable quality, open-source browser based 'office' app? Open Document is all XML right, so it's not like a browser can't read/write the format because its some binary blob..
There's all sorts of debate above about office 365 (some reads more like slick advertising astro-turf - people really shouldn't bite at that stuff) but this could be great for many web based business automation apps. I can think of a few things I've done in the past this would have been great for. I see it's already being built in to Zafara and Roundcube.
Seriously, multiple down votes? I didn't even get to mentioning toe-jam.
There's a demo on the homepage that runs on Sandstorm.io, so you can very easily self-host or use managed hosting via the Sandstorm framework (https://sandstorm.io).
EtherCalc (https://ethercalc.net/, not related to Etherpad) is an OSS cloud spreadsheet app. Demo on homepage, also available on Sandstorm.
Sandstorm has several other office/productivity apps, and in my opinion, is the clearest route to an effective OSS cloud office suite. I am hopeful for LO Online, but tile-based rendering seems like a bad choice. I have no doubt it will be packaged for Sandstorm at some point, but Etherpad is looking much better as of now.