Some of you may know I own my Cirrus with other pilots. For the last year or so to help with scheduling we use a free service offered by Air-Flow at http://www.air-flow.net/
Their site has had a few minor bumps but over all we find it works best than calling each other. It also allows you to schedule dates far in advance as well as block out dates for maintenance.
Our group of 4 has set up a FREE hot mail account and use the calendar for scheduling. We have been very happy with it and the ease of use. Did I say FREE? Actually, two of us can be on it at the same time.
Another group of partnered pilots turned us on to the idea and it has so far worked trouble free. Oh, did I mention FREE?
We’ve used www.aicraftclubs.com for the past two years with a 4 aircraft, 45 member club. In my opinion, the service is excellent. There has been only 1 time that the service was down (only shortly) while they converted to a new server farm. They have both internet and phone access available. I would highly recommend this service!
My partners & I use Yahoo groups. We created a group of our own, which is not accessable by the public. In addition to a calendar, it also provides free-format databases for phone numbers, squaks, etc., and threaded discussions. So far, we’ve had 100% uptime.