So you're interested in donating to charity, but never seem to have any spare cash? Well there's now a painless way of donating to some of your favorite charities, by taking out an Affinity Credit Card.

There are literally hundreds of charity cards available, so we've selected three "environmentally friendly" ones for this article

If you're interested in helping to protect the UK's ancient woodland and increase the number of new trees planted, the Woodland Trust MasterCard may be for you. When you open your account, the Trust will receive a £10 donation from the Royal Bank of Scotland. 

The Trust will also benefit from a 25 pence contribution for every £100 spent using the card.

If the World Wildlife Fund is your preferred charity, the WWF Visa Card may be of interest.

The card has already raised over £1.5M, which has been given to successful conservation projects around the world.

The MBNA Europe Bank Limited is the issuer of the card, which will donate £1 to the WWF when the account is opened, plus a further £1 for every year the card remains open and active. The WWF also benefits from a donation of 30 pence for every £100 spent using the card.

The RSPB is aiming to raise £1M for Britain's threatened wetlands in the next three years, with the help of its card.

The Co-operative Bank, which is behind the RSPB Visa Card will pay £10 for every account opened, plus another £2.50 if the card is still being used six month's later.

In addition, the RSPB receives 25 pence for every £100 spent using the card.

So, if you're interested in doing your bit for the environment, without having to pay a penny, click on the image of the card you're interested in, which will take you straight to the card issuer's site.