Tech: RememberTheMilk, Twitter, and Google Calendar

http://www.rememberthemilk.com/

They make it pretty easy to integrate, I think.  Browse the site (sign up, of course), and then on the homepage there click both the Google Calendar button and the Twitter button, and follow each of their instructions.  When it's all done, you can just IM your Twitterbot something like "Lunch with Julie at 8pm Apr 30" – it'll set up an appointment in itself, and then sync up with Google Calendar.  You can ALSO add their widget to your iGoogle homepage or Google Desktop, if you feel like.