galaxyAbstractor

The firefox addon https://addons.mozilla.org/en-US/firefox/addon/firecoin/ lets users easily donate BitCoins to site owners. It gets your BitCoin address from a metatag named “bitcoin”. It also allows the site owners to provide a message and a URL to a thanks page.
This plugin makes it easy for you to add these tags to your headers.
Please note that this plugin will promote the Firefox addon in a HTML comment in the header, which is only visible if a user would inspect the HTML code. It wont show the link anywhere else.

FireCoin

Easily lets you put your bitcoin address, a message and a thanks URL in the header section, so that firefox users using the FireCoin addon can donate  …

springthistle

Put a simple PayPal donation form on any post or page with a shortcode. The form has buttons for quick donation amounts, the option to enter your own amount, and the option to choose a one-time or monthly recurring donation.

Very Simple PayPal Donation Form

Put a simple PayPal donation form on any post or page with a shortcode.

FireCoin vs Very Simple PayPal Donation Form