I had a python script which could have been easily turned into a mobile app, however I use att and now they require you to use their api. My notes on the subject: http://hardtodetect.com/announce/att-api-and-the-future-of-sms-py/
You could try mysms. http://www.mysms.com/
I'm testing out mysms now, which does both. Cell+tablet application with notifications, and decent web interface.
It does also come with some whatsapp-like bloat I don't need though, but it's not intrusive.