Not all Online TEFL/TESOL courses are created equal.
http://www.tefl-reviews.com is a good starting place to check out the authenticity of courses.

Forums are often peppered with anonymous users claiming that online certs are worthless.
In some cases they can be - depending on the individual - however, we have a very successful history with providing Int.CertTEFL/TESOL certification courses and to date we have well over 1,000 Grads teaching teaching worldwide.

Please feel free to get back in touch through our site if you have any further questions:
http://www.tefl-tesol-online.com
Thank you.

Neville :-)