Thank you for providing a useful donate button (script and graphics).

I do believe the method offered for use could be made more secure for the site operator.  Currently, your site has full access to replace the bitcoin address.  And without HTTP everywhere, there is the opportunity for a MITM to alter the contents, substituting the bitcoin address with another.  Being that these are for donations, I might not even realize that this is happening.

The javascript could be revised so that it could site on my host, or in the same .html as my page.  That would be safer.