Australia
ad supported
http://www.blueskyfrog.com
5 Free SMS a day, Limited Characters. Also paid options available.
http://www.smsfun.com.au/index.php
http://www.freesmsmate.com.au/
Up to 10 free SMS to Aussie mobiles per day
New Zealand
http://www.sms-txt.co.uk/NewZealand.aspx
South Africa
http://za.simplesms.co.za/login.php
Registration required
Nigeria
http://www.abujamobile.com/free-sms.php
Ad supported
Singapore
http://websms.starhub.com/websmsn/usr/createMsgSessionPageShow.do?method=initCreateSession
Only send to Starhub mobile phone subsribers
UK
http://www.o2.co.uk/login?dest=http://sendtxt.o2.co.uk/sendtxt/action/compose
Requires registration and you get 10 free texts
only works for UK mobile phone numbers
For extra texts you have to pay £1.50 for 30: