With this plugin, you will get two links; One link for the image, and one link for the redirect page. Then you can use these links in a forum signature like this:
[url=example.com/wp-content/plugins/p2i/1.php][img]example.com/wp-content/plugins/p2i/1.png[/img][/url]
It also supports shortening the url’s with “is.gd”.