If you are waiting for some electronic parts to be delivered the wait can be agony. It is especially painful when you learn your parts which you desperately need have been sitting in your mailbox for most of the day because the mailman came early… This problem is solved by this Mailbox Wireless Alert Project. Re-purposing an off the shelf inexpensive wireless alarm system is all you need. The wireless sensors have great range and lots of them have phone capability, some can even SMS you when there is an alert. Why re invent the wheel when there is a box of electronics that was built for a different purpose that is adaptable to solve your pressing issue.
Via Hacked Gadgets.