I recently noticed that 'Boomerang' (the free advertising postcard stands that you find in cinemas and other public places) currently have a card with chips on that read "Have you chips and eat them.... FOR FREE!".
The card has a voucher on the back for a free pack of 1KG McCains Rustic chips. The voucher says it has a value of £1.50. Yesterday I went to Tesco and found that these chips are currently on offer at £1 in all stores until the 8th March.
I brought 3 packs (had 3 vouchers) for £3. The lady at the checkout then scanned the vouchers (which are already on the Tesco system, so they just scan the barcode and they work) and each one took off £1.50 from my bill!
So total taken off was £4.50 for £3 worth of chips, so I got 3KG of chips for free and got £1.50 taken off the rest of my shopping for the privellage!
Obviously this deal is dependent on your finding the cards / knowning where a stand is, but if you do, grab a load!!
I will upload a picture asap.