Adding custom Liferay portlet to Control Panel in Liferay 6.1

To add your custom portlet into Control Panel like "Wikki", Polls etc links.
Create a custom portlet using New -> Liferay Project. Choose Portlet Plugin type.
After the portlet is created open "liferay-portlet.xml"

When using Liferay’s Plugins SDK, these files are stored in a standard directory structure:

PORTLET-NAME/
build.xml
    docroot/
    css/
    js/
    WEB-INF/
        liferay-display.xml
        liferay-plugin-package.properties
        liferay-portlet.xml
        portlet.xml
    icon.png
    view.jsp

Add the following highlighted lines in that xml file and your portlet will show up in Control Panel. 

<portlet>
        <portlet-name>mycontrolpanelprtlet</portlet-name>
     <icon>/icon.png</icon>
        <control-panel-entry-category>my</control-panel-entry-category>
<control-panel-entry-class>..</control-panel-entry-class> <control-panel-entry-category>..</control-panel-entry-category>
        <layout-cacheable>true</layout-cacheable>
        <add-default-resource>true</add-default-resource>
   </portlet>

If the portlet does not show for a particular role then assign permissions accordingly.

Hope this would be of some help. Please comment.