You can donate them and the proceeds go to charity. Some shops that sell them have special bins to drop them in - I think I've seen them in Staples. Also, you can get them refilled at places like Cartridge World - cost me about £14 last time for black ink, colour is more, but they've got to be in good nick and not leaking for that. I generally get about 4 refills before they start to get too damaged :)
Many places will recycle them, I don't know if they still do it but in Tesco, for instance you could get an envolope to send them to their recycling unit and the would make a donation to charity. PC world used to do the same but they had collection boxes in their stores. I don't no why but for some reason many places will not take Epson cartridges
Go on google there is a firm in Leeds that pays £1 each and it is freepost.
email them what you have and they will give you a price and a freepost address.
Most places won't accept epson cartridges for recycling, we have to recycle cartridges and toners at work (it's a legal requirement) but we have to throw epson ones straight into the skip.