There are several web based tools that make my life immensely easier. These are things I use to stay (somewhat) organized, informed and save time.
del.icio.us - When I first saw this I never thought I would find it useful. Since I started using it I wonder how I ever got along without it. Del.icio.us allows me to store all my bookmarks on the web, accessible from anywhere. I can tag my bookmarks with keywords to organize them and then I can search and browse the bookmarks by keyword. Very handy when I know what I want, but can't remember the name of the web site. Also, I can view the keywords as a "cloud". The keywords in the cloud become bigger as more items are tagged with that keyword. That helps me see what tag I am using the most.
Google Reader - I use this as my news aggregator and to subscribe to the rss feeds of all my favorite blogs. Instead of jumping from site to site to read all the updates, any new updates are delivered to Google Reader where I can browse them in one, central place. A person needs to have a Google ID use this service.
Google Docs - This is a web based spreadsheet and word processor. It's very handy to be able to create and edit documents anywhere there's a web connection and not have to depend on the presence of a specific office suite. Again a Google ID is required to use this service.
Twitter - Answers the question 'What am I doing?". If anyone wants to know what I'm up to, it's posted at Twitter. Also, I've linked it to my Facebook status so that any Twitter updates also update my Facebook status. This is another tool I never thought I would find useful. However, I've found "micro-blogging" to be an effective way to let people know what I'm doing.
Babel Fish - I have some Italian, Dutch and French speaking friends. I can impress them with my language skills by translating what I want to say with Babel Fish. They know I don't speak their language, and their english is better than mine, but they appreciate the effort and it's fun to learn something new.