someone posted this earlier, i had a email for a non-used abox account offering membership fro £1 (1 month), i logged in under my existing gamertag and extended my xbox live till 21.12.11 by repeating the process.
It does work
Use paypal and keep on adding them up till june 2014 ;)
***Edited by Eldini to add***
Use this offer to get several months of Xbox Live Gold for £1 each.
1. Go to this link:http://click.engage.xbox.com/?qs=ab607ba3c4120cfe21eb6dcfbfe2510a246de17266a9f17f1bd1ae699d26f855ebe169c3ab12778f
2. Pay using paypal or a CC for 1 month for £1.
Keep opening the same link and repeat the process for as long as you can before you get the red error message
(i managed to get 14 months for £14 this time, a few months ago when this same glitch was on i managed 4 months for £4)
3. Unfortunately you HAVE to ring up xbox's free phone number to cancel the autorenewal.
This step is vital or they'll charge you £6 a month later on. (You still need to cancel even if your Credit Card expires before then. They can still get the money from your bank.
Ring 0800 587 1102 to turn off autorenewal, more information available here: http://support.xbox.com/en-gb/pages/call-us.aspx
And please ignore the idiots who say this will get you banned, it won't, thousands of us did this a few months ago and had no trouble at all because of it.
It's simply an offer that Microsoft have forgotten to limit to once per account...