My new favorite web app is TimeBridge, a great utility that allows me to share my Microsoft Exchange calendar with anyone I choose.
In the past it's been difficult to set up meetings with my clients since they can't view my calendar. So I send them a few available times and they see if it works with their schedules. Often times there isn't a time that works so we have to repeat the process until something sticks.
Now I just send them a link to my online TimeBridge calendar and they can view my schedule and set meeting times for me. A small Outlook extension keeps both calendars in sync and up to date. Check it out at: http://timebridge.com