Bitbucket actually has <a href="http://www.bitbucketcards.com/" rel="nofollow">http://www.bitbucketcards.com/</a>
btw, <a href="http://gitlo.co" rel="nofollow">http://gitlo.co</a> is cool for github issues
Jira Agile already includes this functionality for Software Development projects. A Board is created for these projects which exposes issues in this kind of interface.