Google Calendar is really great. Really. Sign up for an account now. You don't need a GMail email address but it is useful as they go well together. If you live in the UK you need an invite (just ask me) to get a GMail email address. You don't need an invite to sign up for the calendar.
Google Calendar does all the usual things calendars do and more. The interface is entirely web-based so you can access it anywhere. It's really easy to use too. Just click on the date or time you want a new appointment / event and it'll start creating it.
Google allow you to have multiple calendars. For example I have a main events one and one just for birthdays. I can share any calendar with the world or just my friends. Here's my friends birthdays in XML and iCal. You cannot edit them but my some of my friends can edit our joint one.
You can also search other peoples' shared calendars and "subscribe" to them. For example Tom has Arsenal football things. Hopefully Google Calendar will become imensely popular and our university departments (e.g. Computer Science, Careers service, the Guild, XNet) will publish important events which can be viewed by students but only be edited by staff (with changes showing up immediately).
The interface is amazingly slick. I love the way you can select days or weeks in the mini-calendar to immediately customise the main view. There's also the usual Google search box meaning if you've forgotten when an appointment is you can easily find it. Finally there's a print option which actually creates a PDF file.
It's still in beta (meaning there's a few bugs but is fairly stable) so there may be more features on the way.
To improve it I can only think of:
- Have everyone use it. It's be great to know when people are around / busy. Also you could see who's planning on going to the pub that evening! It'd be useful for organisations too.
- UK text alerts. They do this in the US but mobile operators charge companies lots to send texts so I doubt Google will do this for some time. Until they make the Google Phone...
- A todo system. Not really used but would be useful. Maybe just a small notpad thing.
- Better code / stability. This will happen; soon I hope. The beta sometimes doesn't save things and it takes up lots of memory sometimes.
- More color options. Not exactly important but where are the bright colors?
- Tags for events and tags for celendars. Or search terms for events. For example I could search for every even mentioning Exeter University and just see them. I don't want to have to subscribe to every band which say they're playing here on some day, then the rest of the calendar is useless to me.
- Re-arrange the days of the week (with drag and drop). I'd like Thursday to come after Monday, then it'd almost be the end of the week on Monday. Google Calendar currently doesn't support this but I hope it does soon.
- Featured calendars, search by location, topic, etc.