Web-based Calendar and Appointment system

I'm looking for recommendations for a web-based calendar system.  If you're using one or know of one, please post the info in the comments below.  This is my ideal system:

1. Low monthly cost or free
2. Can track appointments for multiple people on one calendar (multiple users)
3. Ability for clients to make appointments online, but not see our personal schedules, only times that are available

Would love to get links to your recommendations and why you think it's great.

Thanks!

Comments

[Philippe Borremans]

Hi Denise,

You should find something you like in this list of 131 Web2.0 products and services:http://www.listible.com/list/complete-list-of-web-2-0-products-and-services

[Paul Wagner]

Hi Denise:

I get this question all the time from Outlook students and I send them to 3 places. I have opinions on each, too long for this space.

http://www.shareoutlook.com
https://secure.dslextreme.com/medusa/exchange/

www.1and1.com/ (click on Exchange)

Paul

[Denise]

Thanks for the recommendations. I don't use Outlook so I'm looking for something other than that. I've checked out the list of Web 2.0 stuff and it's amazing. I'm going to try out www.Calendarhub.com and see how it works for me.

[Tara McGillicuddy]

I have been using Appointment Quest for the last year and I have been very happy with it.

">http://www.appointmentquest.com/?pk=5010030855">