Check out this application, it's a location based reminder application for Blackberry smart-phones.
WhenImClose will trigger a reminder when you are as close as you set it to a certain point on the globe.
For example, you don't know when you will be home but you want to get milk from the store when you do. With WhenImClose, you don't have to worry about that anymore. It will remind you to get milk as soon as you're close to home.
