http://ping.fm/MRVA8
This app is awesome. Send text messages via iPhone / iPod Touch for free.
Read below:

UNLIMITED TEXTING - for FREE
✓ why pay $5.99?
✓ why limit yourself to only 15 texts/month?
TEXT on YOUR IPOD TOUCH
✓ no cell phone needed
FREE to DOWNLOAD, FREE* to USE
✓ no monthly fees for text or data plans
NEW! TEXT TO CANADA
✓ We've added Canadian carriers - You asked for it - we delivered!
✓ Text to Canadian numbers for free - just like US numbers
✓ Replies from Canadian numbers to textPlus will be subject to standard text
rates from their carrier. No international charges

PERSONAL COMMUNITIES
✓ Name your class or clique - reach everyone with only one text
✓ Text the group name to 60611 to join in from ANY phone