Public web applications and knowledge workers
The key thing is that all of these public web services allow you to export your data for archival backup, use in utility scripts and programs, etc. Most also support, in addition to manual data export, web service interfaces.
The only work that I perform "locally" is programming in Emacs+Common Lisp, various languages in Eclipse, and writing large documents using either Latex or OpenOffice.org. Even for "local work", all of my working materials are stored on leased managed servers in subversion repositories.