AnyDay.com
An excellent free service, AnyDay.com can help you get your life organized. Sign up and you'll get your own private online "DayPlanner" service that includes a calendar; an address book for your contacts; a place to keep track of your to-do lists; and your own personal reminder service. You may also easily synchronize your data here with your Palm Pilot, as well as other hand-held organizers. 

ScheduleOnline
A number of sophisticated free scheduling services have sprung up lately on the Web. ScheduleOnline is one of the best (and easiest to use) that we've seen yet. This fully-featured service, which targets small companies, lets you perform a wide range of helpful tasks. Here, you can schedule meetings and tasks, create "to do" lists, broadcast E-mail invitations, send E-mail reminders and lots more. 

DateReminder
A handy new free reminder service that is easy to set up and use. Just sign up and select a subject, date, message and frequency and you're all set. You may set up as many reminders as you want. Now you don't have any more excuses to miss that important appointment! 

When.com
This ambitious site (now part of the America Online empire) offers a useful free personalized event planning and calendar service. Their personal online calendar lets you keep track of appointments, birthdays, anniversaries, reminders, and upcoming activities in a "secure, online environment." It's accessible anytime online and let you combine your personal schedule with When.com's huge event database. When.com also offers a free group calendar, designed to help groups of people stay in touch through a common source for key dates and shared events. Helpful for anyone from volunteer groups to small companies to soccer parents. 

PlanetAll
This very useful service, which is part of the Amazon.com empire, lets you receive automatically updated information and reminders about your contacts. This service lets you keep on top of things: birthdays, anniversaries, etc. PlanetAll also allows you to build a private address book that's always up-to-date (and which you can access anywhere).
PlanetAll offers a useful feature that allows you to exchange address book data with your Palm Pilot or with Microsoft Outlook.