When you purchase any Doctor Who item from the gift section (not the toys) of the current Argos catalogue you get the chance to claim a free* TARDIS Emergency Fund. I haven't bought any gifts but some have been bought for me as Christmas presents & the form that you need to fill in (it's in the box with whatever you've bought) was passed on early so I filled it out & sent it off.
What you get is this fab looking TARDIS key ring, but it's much more than that. If you pull the bottom out you find a space to put a rolled up bank note that you can then carry around with you as an 'emergency fund' (hence the name!) Spent all the money in your purse/wallet ... wait ...you've got money in your TARDIS to pay for a cab home (well that's the theory anyway!)
It's a great idea & I do love my TARDIS keyring but ... it is a little heavy & it is quite easy to knock the bottom out. These are only small gripes though because they are easily worked around by carrying it in a pocket or handbag.
*you have to pay £2.50 P&P. It has an RRP of £4.99 so presumably you can purchase it, though not from Argos (my apologies I've forgotten where I had to send the form, but if I remember or stumble across a website I'll let you all know