Beacon is a location-based reminder service. You hook up your Google Latitude account and set a reminder for a latitude and longitude. When you're close to the location, Beacon will send you an SMS with the reminder.

I used it to send myself shopping lists when I was close to CVS. Never be without toilet paper again!

Worked well when Latitude, cron, Twilio and AT&T were able to beat my walking speed.
Weekend project.

Uses: Latitude, Twilio, cron, MongoDB, Tornado