Here's a list of Android apps that I have looked into and tried some only. If you are looking to send text using bluetooth then I would look into the apps on the top list.
The apps on the bottom list were more useful to me. BrowserTexting was what I used from all computers, but now appends a message at the end makes it no so attractive.
WIFI / USB / BT Links
DesktopSMS - Requires JAR client thru USB or WIFI
EasySMS - Works on any Browser
RemoteSMS - (http://www.ct-designs.de/android/remotesms/) Uses Browser
Remote Desktop - Uses browser
Texdro - Requires Java and Browser, but on LAN
Thru Gmail or Other Services
CrossTxT - requires Cloud account on website http://www.crosstxt.com/ (closed Beta May 2011)
DeskSMS - uses GMail account (cost $$)
mySMS - Paid service over Cloud
SMS2PC (http://www.scottstraughan.com/sms2pc/) - (cost $$$) Requires client install and works over Internet via 3G
(2 - crude) MightyText - Works on Chrome Browser with GMail Account (uses Data)
(1 - nicer) BrowserTexting SMS via browser (http://www.browsertexting.com/) - Works on any browser over Internet via 3G (Dec 1, 2011 -> Separate b/w Free and Premium. Free has limitation and appends sig at end of text)