Hi Suzanne:
I personally have not used Airset, but from reviewing their website - it looks pretty neat. For me, I personally use Google for my online calendar and actually use it for one of my clients.
I like the simple user-friendly interface and the fact that you can sync it with any of the other online calendar programs out there (
www.smartcal.com or
www.backpackit.com) or even your Blackberry!
The only con I have about Google calendar is having to log in each time to add an important event versus entering the event into the Blackberry!
Another online calendar to check out online is
http://www.famundo.com. I haven't used it but it looks neat. Good luck and let us know which one you decided to go forth with!