SMSDroid is a service that let's you access and send SMS messages and view contacts over a TCP socket (or via good old telnet :)). Supports password login.
I've noticed a lot of people rating this application down because they don't understand how it works, so I've added a small tutorial at the bottom.
!! Most providers do not allow this over 3G. Use WiFi. !!
Telnet in and type help to begin.
Update 0.2.0: Added getSMS and getContacts features + bugfixes.
1) Start SMSDroid on your handset
2) Set a password
3) Start the service
4) On your windows machine hit start -> run and type in 'cmd' then click ok
5) In the new CMD window type 'telnet' followed by the ip and port show in SMSDroid. Example: 'telnet 10.0.0.52 7777'. Then hit enter. *
6) Now enter your password and when you get to the prompt enter 'help' and hit enter to get a overview of the commands available.
*) If you get a message saying telnet does not exist you're probably running Windows 7. Please google 'telnet+windows+7' for a bunch of guides on how to add telnet to W7. It's quite easy.