starmsg.com 

Starmsg.com is a freeware that allows you to send text sms messages from your PC to mobile phones all over the world. You can set the delivery time for text messages, send Flash SMS or anonymous text messages. Universal charges apply.
sms messaging txt sms messages flash messages text messaging inbox text messages

eusms.net 

eusms.net is a free software for Microsoft Windows to send text messages (SMS) via internet. You just pay the messages you send. You can even set the delivery time, send Flash-SMS or anonymous messages.
sms text messaging txt text messaging inbox