Log onto Twitter from your computer and set up your mobile settings. Twitter will first send you a confirmationtext to make sure its the right cellular number.

Twitter texts will come through on the code 40404. These count as normal texts. You can send messages also to 40404 and this will post on your twitter page as your tweet updates for your followers to see.

I have not used Gaia alerts so I cannot tell you how those work. See if they have an option for mobile settings.

Other sites that do are facebook and myspace. You can send your updates through texts after setting up mobile settings on your accounts.