Ebay doing a promotion for anyone who's bothered, anything under £5 free for first 50,000 people - Enter code CUKFB1 at checkout. https://www.facebook.com/eBay.co.uk
It doesn't go towards shipping though.
I just got myself a jar of plamil chocolate orange spread for free. :)
Find something for £5 with free delivery or just get a fiver off of your next purchase.