The rest of the alternative cloud-based office editors
An alternative to hosted Office services are Web-based document editors.
Google's Drive (free with a Google account) can only edit text and do rudimentary formatting -- and only for files saved in Google's own format in your desktop browser. The same is true for spreadsheets; there's no formula editor, for example. And it can only view presentations. It's not the editor as promoted by Google.
The free AstralPad provides moderate editing capabilities -- more than Google Drive, less than hosted Office -- but is very slow, allows only two open documents, can't print, requires manual keyboard activation, and has a confusing interface. It does allow access to Dropbox and Google Drive files.