I have been entering the free Sky Lotto's over the past two weeks and have won free scratchcards. I tend to win a few pennies each time.
On Sky Lotto there's a weekly on Friday and daily free draws, and while you are there go to the Sky Vegas section for a free 'prize machine' daily free competition and currently on Sky Bingo there's a similar free daily draw.
Prizes are normally small - so far in April I've won the princely sum of £2.71 (tax free!) from the Sky free competitions - but hey it's a couple of minutes of distraction each evening and it all adds up.