From OpenStreetMap Foundation

OpenStreetMap is a non-profit organisation (but not a registered charity) that relies on donations for much of its funding. If you think that our aims are worthwhile then please donate according to your abilities to help us keep the servers running.

We have a UK bank account and also run a PayPal account. Generally, if you have a UK bank account it is best to make a standing order or electronic funds transfer to our bank account, we can also accept old-fashioned cheques if you can’t do it electronically.

If you do not have a UK bank account then, except for large amounts (over €250/$250), it is probably best to make the payment via PayPal although it does depend on what charges are incurred by your own bank.

Here are more details and account numbers: