I used one yesterday - cjc99d - which is still active and works for up to 3 .com's at 72p, it also works if you've used the other recent codes giving this same price (I've got 9 .com's all at this price now)...or you could be sneaky and reg under different accounts and just move them between accounts
Only weird thing with it is when you try and check out it always seems to freeze if the currency is GBP (this might just be me though) - I found that by changing the currency to US it worked perfectly (was around $1.20)