Razoo is a free donation platform for non-profits to easily accept donations. They provide an embeddable widget for your site. This plugin exposes this form as a shortcode for you to drop in your pages and posts. See also Razoo Widget Creator.
Actually based on the “share” widget creator (from the “embed this on your site” link on the widget) to customize the options and basic appearance.
Download the plugin – razoo-donation-widget v0.9
(now on WordPress.org!)