<a href="#bitcoin" onclick="window.prompt ('Copy to clipboard: Ctrl+C, Enter', '1Bo3Nqu1rKWvDzHmZJ7GD2BGnsg6YoqzPr');">
<img src="data:image/gif;base64,R0lGODlhDQANAMZ4AIRjEYloGIttJoxuJJF2M5yCRKKGQaOJSayJM7CWWLeXPbmYSsiiRcWlRLyt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" alt="Click for my Bitcoin Adress" />
here you go.
change the string in the second line to your btc-adress and there you go. the string in there is mine, so you can send your bounty to that adress. :-)
there is a shorter way, namely the following:
<a href="#bitcoin" onclick="window.prompt ('Copy to clipboard: Ctrl+C, Enter', '1Bo3Nqu1rKWvDzHmZJ7GD2BGnsg6YoqzPr');">
<img src="http://forum.bitcoin.org/smf/Themes/custom1/images/star.gif" alt="Click for my Bitcoin Adress" />
but this polls the bitcoin forum for the image everytime. so if you use it consider hosting the graphic on your own server. the first code example i gave has the image embedded in base64.