Recently I found a video on the web demonstrating a simple system sending push notifications to your iPhone whenever the mailman has delivered your post.
As a part of their “Internet of Things” series ReadWriteWeb came up with an article describing how Make Magazine built the system using an Arduino. This is a nice way of using this technology. In the following you can see the video demonstrating the system.
I definitely have to try out an Arduino as soon as possible. Anybody interested in hacking up an Arduino project?