Xmarks Acquired by LastPass
blog.xmarks.com
blog.xmarks.com
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?
If you go to the Steam menu -> Settings -> Downloads+Cloud, then check the box for enabling steam sync for games that support it.
It was introduced to Left 4 Dead late 2008. I'm not sure how widely it's used at this point.
In settings you can enable it at the bottom of the Downloads + Cloud tab.
Also, don't give up on a web photoshop just yet!
The other big thing lacking is integration: I can't save a Google Doc directly to my Dropbox account, proper OpenID support isn't widespread, when Photoshop does come to the cloud, I definitely won't be able to upload directly to Picasa and Flickr, and nobody seems to be interested in enabling the seamless (secure) sharing of data between web apps.
I use iMacros for Firefox + Dropbox for all web logins
and Keepass + dropbox for all other passwords.
Both programs store the passwords AES encrypted, and are thus safe to use with dropbox