In case you haven't heard about it before and are planning some Prime Day purchases tonight!
You can pick a charity and they get a small donation from what you spend. There are lots of organisations to pick from including Women's Aid which I've selected on my account.
0.5% is a tiny amount but if more people sign up more money will be donated and more charities will benefit 
"AmazonSmile is a website operated by Amazon with the same products, prices and shopping features as Amazon.co.uk The difference is that when you shop on AmazonSmile, Amazon will donate 0.5% of the net purchase price (excluding VAT, returns and shipping fees) from your eligible AmazonSmile purchases."
LINK:
www.amazon.co.uk/gp/help/customer/display.html?tag=mumsnetforum-21&nodeId=202035970