If you're looking for a way to remotely control an Arduino without the Internet - this method by Nico may be suitable. He takes us back to the times of using DTMF tones to control things (remember those answering machines?) with his "DTMFduino". It uses the venerable CM8870 DTMF decoder IC which can easily detect DTMF tones over a phone line and relay the results to an Arduino via digital outputs. From that point you can create your own plans with regards to what the Arduino can control, for example relays or other switches. This could also be useful for creating an internal device control system with unused or decommissioned telephone wiring.
Note that connecting your own hardware to the public telephone network may not be legal in your areas - however all the details can be found in the project github page. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're looking for a simple way to control many relays from your Arduino, without using up all your digital I/O pins - check out our Relay8: driver shield:
So what is the RELAY8:? It's a new Arduino shield that allows you to drive up to 8 relays from your Arduino using just 2 I/O pins with this shield. It communicates with your board using I2C, so you can even stack several shields together to drive 16, 24, or more outputs! Includes back-EMF protection and works with a wide range of relays. Perfect for home automation projects! For more information and to order, click here.