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. Other have already contributed a bunch 
(Remember for SharePoint 2013, 2016 you might want to add "15", "16" respectively after "/_layouts/" but if you don't SharePoint will take care of that for you) .. Also some of these are turned off on Office 365 SharePoint online.
Site collection level recycle bin:
/_layouts/15/AdminRecycleBin.aspx
Site level recycle bin (Added by Steve Stewart):
/_layouts/RecycleBin.aspx
Recreate default site sp groups (Added by Neal Bongers):
_layouts/15/permsetup.aspx
Load document tab initial (Added by Dominik Gempeler)
?InitialTabId=Ribbon.Document
Delete user from Site collection (on-premises) (Added by SamDavid):
/_layouts/15/people.aspx?MembershipGroupId=0
Display list in grid view. 'True' is case sensitive (Added by Antoine L.):
?ShowInGrid=True
Quick Launch settings page (Added by Ishani M.):
/_layouts/quiklnch.aspx
Navigation Settings page (Added by Abdur Raheem):
/_layouts/15/AreaNavigationSettings.aspx
Sandboxed Solution Gallery:
/_catalogs/solutions/Forms/AllItems.aspx
Workflow history hidden list:
/lists/Workflow History
Filter toolbar for Lists and libraries (Added by Asimaili):
?Filter=1
Site usage page (Added by @Dnyag):
/_layouts/usage.aspx
Site content and structure page (Added by @Dnyag):
/_layouts/sitemanager.aspx
Site settings page (Added by Aowworld):
/_layouts/settings.aspx
View all site content page (Site content) (Added by Aowworld):
/_layouts/viewlsts.aspx
Manage site collection features - CASE SENSITIVE - (Added by Vardhaman):
/_layouts/ManageFeatures.aspx?Scope=Site
Manage site features (Added by Vardhaman):
/_layouts/ManageFeatures.aspx
Get the version of the SharePoint server (Patch level) (Added by: John Liu):
/_vti_pvt/Service.cnf
Web Part Maintenance Page (Added by: Ricky):
?Contents=1
Show Page in Dialog View (Added by:Ricky):
?isdlg=1
Application page for registering SharePoint apps
/_layouts/15/appregnew.aspx
Save Site as a template
/_layouts/savetmpl.aspx
Sign in as a different user
/_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
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
_catalogs/users/simple.aspx
Force displaying the user profile in the site
collection:
collection:
/_layouts/userdisp.aspx?id={UserID}&Force=True
Site hierarchy page (lists of sub sites) - (Added by community contributions)
/_layouts/vsubwebs.aspx
/_layouts/1033/vsubwebs.aspx
