: I've found Opengroupware quite fragile, too, and I'm not really a huge fan of it; I look forward to future developments, though. Have you checked out moregroupware
at all? It's a project I'm involved with (plug plug), but IMHO it's the nicest web-based groupware out there; the interface is consistent, logical, and easy to use; the backend is very, very capable (the user/group rights system rocks); and it's under /very/ heavy development; new features continually (I'm currently working on a new module right now; the company I currently work for have a few commercial modules, such as stock inventory, which I'm trying to get GPL'ed). Grab a CVS snapshot. There's currently two calendar modules; Calendar2, which is based off PHP iCalendar, and the original Calendar1 module, which is currently being rewritten to be a far more corporate calendar. Calendar2's currently the most usable, and it's quite capable for group calendaring.