I am posting this on behalf of dsp(http://forum.bitcoin.org/index.php?action=profile;u=31526) a newbie who is restricted to the Newbie forum:

Quote

Cant post to this thread: http://forum.bitcoin.org/index.php?topic=25982.0
Want to post a link to one of myprojects:
http://www.otp2fa.com
I Sent this to mtgox told em they could use it for free/cost.

Oops, dsp sent me his link, but I didn't understand that he couldn't post it, due to his n00bie status.

Also, jaakkop (http://forum.bitcoin.org/index.php?topic=26124.msg326768#msg326768) mentions this tool from Google:

http://code.google.com/p/google-authenticator/

Another passcard service I found, with an open source algorithm and mobile support is:

https://www.passwordcard.org/en