In case anyone wants to make any extra money through answering survey questions, I highly recommend:
It's Your View
and, to a lesser extent,
The former sends you a cheque for £50 every time you reach 50 points (I am on 19 after 8 months or so, but I have not taken full advantage of the surveys sent to me), and the latter has various rewards, e.g. Amazon vouchers, free CDs, ...
Also, every once in a while
has some cool free samples, cinema ticket offers, and general competitions (which I don't suggest you enter as it seems you just get spammed, and I don't trust most of those sites anyway).
The Graduate Panel
The Student Panel )
pays for your survey time in Amazon vouchers.
As Tesco says, every little helps.