What have you found to be the most useful and/or interesting online service?
ThinkFree Office has been very interesting as a word processor as well as a few additions.
It's a bit different then other online office sites in that you can download the office suite to your desktop and work independent of the online service. And even offline you can work on documents, keeping a copy on your computer as well as online of all your documents.
It has only 1gb of storage for documents and syncs with the desktop application.
But anyway, I have quite a few online services bookmarked, but this one stood out as different though MS Office has an online deal I haven't tried.
ThinkFree Office is free.http://www.thinkfree.com/