I work with serval clients as a freelance wrter, and as a contracted virtual assistant, and would like to know other ways to keep my days more organized and efficient than just Excel.

This is rather simplistic but I've been using Google Calendar like crazy and synching it with my Blackberry. I get an event reminder every time I have a deadline coming up on my phone. And can organize my day quite nicely. All I have to do is update the calendar on Google and then it updates on my phone. I can check my schedule from my phone constantly or from any Internet connection. Also, when I'm about I add appointments and deadlines to my phone and it also updates to Google.