I posted a list of all the published SMS codes. Here's a link to rhe Digg story. http://digg.com/tech_news/List_of_all_SMS_Text_Codes_from_COKE_2653_to_THEHUT_843488_Pizza_Hut
Only what you provider charges for sending a text message. Unless you request something, for instance if it was a ringtone service If you send a blank message to the number it should reply back with the services available. Most of them have web sites and are listed on my web site. http://clockworkcs.com/smscodes/ thanks for asking.
Nice, I've never considered using these before (due to a fear of extra charges to the cell phone bill). Though.. I'll consider it now if it makes things more convenient.
The only ones I have seen that get you are for chatting, ringtones or content. Anything from Coke, Starbucks, Google any reputable company is not going to make you subscribe to anything.