Google Calendar - another great thing among the 23. And another permanent gadget on my iGoogle page. Like the Thing 5 - very simple to create and maintain. Possibility of sharing it with colleagues, friends and all the advertised flexibility and applications of calendar definitely make this Thing very useful (I haven't explored it all yet, but if I only had more time...). Reminders sent via email? Yes, but I would rather have them sent by SMS, but then the calendar would not be free, would it?
So far all the "THINGS great and small" prove to be rather great, especially those small ones, the gadgets. I am not sure about blogging (maybe? later? in future?), and I am a bit scared thinking about twittering. Are we all going to turn into nightingales?
PS. To Girl in the Moon - thank you for the "23 Things Cambridge" bundle :)