I want to create a url from a plugin. eg. The new url will be http://example.com/slug-set-from-plugin , which will output content from the plugin methods. Is this doable?
Use Rewrite the API , in your case: add_rewrite_endpoint(). See this example for more details .
add_rewrite_endpoint()
Try this Custom Permalinks Plugin - http://wordpress.org/extend/plugins/custom-permalinks/