I love the fun details on Ubuntu’s donation page. There is none of the boring one text field, asking us to enter an amount. Eight sliders ask you to ‘customize’ your donation amount for various sections of the project. The copy is great too! And there’s more.
As you adjust the sliders, the contribution amount changes and shows nerdy, quirky stuff that your chosen amount is equivalent to. The quirkiness increases with the contribution amount :)
Wikipedia can take some hints here.