On Howtogeek i read this about reminders that are triggered when you enter a location: Follow the link if you need the pictures.
Unlike most reminders that remind you to do a certain action at a desired time, GeoNote gives you reminders when you enter a location. If you’re a big fan of location-based services, then GeoNote is the perfect reminder for you.
GeoNote is one of the few Geo-Reminder applications that are available on the market for free. Its simple interface allows us to create To-Do list quickly. Just click the “Add Location” button to add your first note.
Each reminder has three parts, a name, a location, and some notes.
Tap the location field and attach the exact location for your task using a map, a GPS, or an exact address. The address is probably the best option when you do not have any GPS coverage in your area.
Once you have filled the task location and address, you should put some notes, and configure how GeoNote should notify you on your pending task. You may choose to have GeoNote to notify you when you are leaving, arriving, or within a particular time frame on your location.
In this example, we setup GeoNote to remind us to pick up the latest edition of Linux Journal Magazine from Borders when we are leaving the supermarket for approximately 100 meters.
Tapping the save button brings you back to the main screen and save your task to GeoNote.
The top buttons act as a quick control panel for GeoNote. The light bulb turns GeoNote on and off. The locator buttons let you switch between GPS, when you tap the satellite button, and WiFi, when you tap the radio tower button.
Make sure that GeoNote is turned on, and you have set the appropriate locator button; otherwise, GeoNote will not notify you on any pending tasks. Slide down your status bar when you see a small flashing GeoNote icon on your task bar to read GeoNote’s notification.
Some people still prefer the standard time based reminders, such as calendars, and others prefer writing their To-Do list on a paper notepad. We like Geo-Reminder because it is a great companion to our standard notes and To-Do list. Feel free to share your thoughts on location-based reminders in the comments section.