How can I send SMS messages through PC programatically? Or there a way to send SMSs through a PC programatically?
Alternatively: is there an android application that exposes an API over a socket (REST or otherwise) that allows one to send SMSs (and possibly other functionality)?
We have a similar question here that asks abour forwarding incoming messages to the PC over a HTTP interface.

Again, I can suggest MAXS or GTalkSMS which is like a remote control for your phone over XMPP.

Disclaimer: I am involved in MAXS and GTalkSMS