I know someone already posted a link to Pinecone Research previously but I've just had an email from them to say they're expanding again so I thought I would post a new link just in case the old one no longer works.

Pinecone have just changed their rewards system as well. You still get £3 for every survey but you can now save this up if you want to and receive it as vouchers (or still as Paypal if you want to).

Very good survey site, I'd highly recommend registering with them if you're not already registered.