Pinecone Research will pay you a £4 voucher for each survey that you complete for them. The vouchers can be used in a wide variety of shops such as Boots, Tesco, Burger King etc.
Pinecone tend to send out survey invitations once or twice a month and these should generally take no more than 15 to 20 minutes to complete. Sometimes they even send you the vouchers in advance of you completing the surveys.
This is one of the best survey companies out there but unfortunately because of their popularity they are not always on the lookout for new member but keep checking their website in case this changes.