Some times you want to jump right to a specific system list, page or go to the edit mode in a SharePoint site. I wanted to list all the famous urls I used for the past years and ask you to tell me about any other ones you know to add it here in the list:
Sign in as a different users
/_layouts/closeConnection.aspx?loginasanotheruser=true
Enable SharePoint designer
/_layouts/SharePointDesignerSettings.aspx
Welcome Page (Default page settings)
/_layouts/AreaWelcomePage.aspx
Change Site Master Page
/_layouts/ChangeSiteMasterPage.aspx
Page Layouts and Site Templates
/_Layouts/AreaTemplateSettings.aspx
Master Pages library
/_catalogs/masterpage/Forms/AllItems.aspx
User Information List
_catalogs/users/simple.aspx
Quick Deploy List
Quick%20Deploy%20Items/AllItems.aspx
Open Page in Edit Mode
?ToolPaneView=2
Taxonomy Hidden List (MMS)
Lists/TaxonomyHiddenList/AllItems.aspx
User Information List:
_catalogs/users/simple.aspx
Force displaying the user profile in the site collection:
/_layouts/userdisp.aspx?id={UserID}&Force=True
Aryan Nava 
Close a faulty web part on a page: ?contents=1