Sending SMS texts to friends in the US can really be a hassle if you live abroad. Some countries support it, some carriers support it, many do not. And even if you can do it, it can be expensive.
Google Labs to the rescue!
There is a (new?) feature to Gmail, available in the Labs tab of the Settings, that allows you to send texts to US cellphones via the chat client in Google. Here's what you do:
1) Log into your Gmail account (duh).
2) Click on "Settings" in the upper-right.
3) Click on "Labs" in the dark yellow bar at the top.
4) Scroll down until you see this:
--And click "Enable"
5) Return to Gmail, sign into chat, and enter a US cellphone number (include the "1" for long-distance) where it says "Search, add, or invite." It will probably ask you to give this contact a name.
6) Type your text and hit send!