I use Google Calendar a lot. Both for personal stuff originally, and then now also for work.
I wish all my frickin' invites automatically went to Google Calendar in the default unacknowledged question mark state. Email doesn't work... if I'm too busy when the invite email arrives and I forget to add it to my calendar, I miss the event. But I do poll my calendar regularly.
Summary of where I get invites from:
- Google Calendar -- works, obviously
- Evite -- dear God, I wish they had an API so I could cron a job to sync my evite to my calendar. Has anybody wrote a screen-scraping module?
- Upcoming.org -- well, they can export to Google Calendar, so that's good, and I don't really get invitations from this, so no real beefs here.
- Crush3r -- great site. wish its invites would show on my calendar somehow. (attach .ics file to emails? will gcal pick up on that?)
- Facebook -- it can export to Gcal, but I have to log in to Facebook. I want the email to add an event.
- Pownce
Plus, I want gcal to be my central RSVP point, and then have some server-to-server protocol for sending RSVPs.
One can dream.