The Largo Donate Widget allows you to place a donate message and button in any widget area. Here it is in a sidebar:
The button links to the URL of your donation or payment processing page. You can set a default button text and URL in the Appearance > Theme Options > Basic Settings menu. If you set this it will also display a donation button in your site’s top Global Navigation bar.
The default button text and payment page can be overridden on a per-widget basis if you want to show different messages on different pages/sections of your site. Or if you don’t want to display a donation button in the top Global Navigation, you can use only the Largo Donation Widget: