Very limited, only 1 url. Have to goto tools\addons\extension\options each time to change 1 url. This needs a drop down list of at least 5 url's that you can set and access from the sidebar.
Also the name in the sidebar to me looks and sounds terrible "Custom URL", something like "My URL's" is more descriptive. Or better yet let the user change the name in options to suite there need. My Pages, My searches?