Use you AIM account to send free text messages!

I haven't tested this out to on international (outside of U.S.) phones, but using your screenname on AOL instant messenger you can send sms messages through AIM and even hold a conversation!  Make sure you the person who you are trying to send text messages have either some sort of text messenging plan, because they will get billed for regular text messaging usage (normal 10 or 15 cent per text message).  But other than that, there isn't any fee's to worry about (Again not sure about international).

To do this, simply log onto your AIM account, and start a new message (or add a buddy).  If the phone number of the person you are trying to text message is 555-666-7777, than just just add a plus sign in front to initiate a text message, for example, add buddy user +5556667777

and just type in the message and hit SEND.  This is a very good alternative if you just want to chat with a person using text messaging and not burn up your own text messages on your phone (or if you dont have a plan).  Enjoy!