Hacking inexpensive GSM modems to send text messages
If you need to get current data from a remotely-located Arduino that doesn't have Internet access, one option is to use a GSM module of some sort. There are a few on the market, however the retail costs amount to over $100 once the required parts are accounted for. One inexpensive solution has been documented by Michael Finch - who describes how to modify a very cheap GSM USB modem for use with an Arduino. You will need some fine soldering skills, however the savings will be worth it.
For more detailed information and instructions, check out Michael's excellent notes here. And we're on twitter and Google+, so follow us for news and product updates as well.
If you're planning on using the modem as described above, an ideal matching Arduino-compatible board would be our Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound and knock detection: