WebParts Galerry
[Siet_Collection_URL]/_catalogs/wp
Masterpages Galerry
[Siet_Collection_URL]/_catalogs/masterpage
To change masterpage of a site/subsite
[Siet_Collection_URL]/_Layouts/ChangeSiteMasterPage.aspx
List of WebParts sitting on a page
[Siet_Collection_URL]/Pages/[PageName].aspx.aspx?contents=1
Site Content & Structure (SiteManager)
[Siet_Collection_URL]/_layouts/sitemanager.aspx
Images in SharePoint Image Mapped Folder
[Siet_Collection_URL]/_layouts/images/[Mapped_Folder_Name]/[Image_Name].[Extension]
