Go SMS Pro now offers that as a feature. When you go into the app, you can make an account on goChat and enable
Web Go SMS in the apps tab. Once you have done that, you can log into your gochat account on http://webchat.goforandroid.com, and txt from there. It will send the message through your phone to the person whom you are trying to send the message to. This way, there will still be a record of the conversation on your phone, so you don't look back one day and wonder "what in the world was I talking about?... And why was this person txting me so much if I wasn't txting back?..."
The two things I like about this are that it doesn't require me to plug my phone into my computer, it does it wireless through the internet, and, Since you send the txt messages through a website instead of a program, there is nothing you have to install on your computer, and it makes no difference what operating system you use. In addition, this allows you to txt from any computer, not just the ones you install any given software on.