LastPass and XMarks or Firefox Sync (and I think Chrome has similar) takes care of keeping your browser the same, independent of location. Dropbox can keep your important files where ever you want (up to some size). Netflicks and various music streaming services can take care of media being ubiquitous. Email and other communications are more often than not tied to an online provider.
So, what parts of your computer can't you get from cloud services if you want? Gaming still seems to be a large one, although OnLive supposedly fixes that. Large applications like Photoshop aren't necessarily replaceable by WebApps. What else?