This will start out to be an incomplete list, but should grow with time.
These are links that are sometimes handy to have when the UI doesn’t display them.
|Path and file||explanation|
|_layouts/viewlists.aspx||Same as site actions->View all content|
|_catalogs/masterpage/Forms/AllItems.aspx||View master pages for this site collection.|
|_layouts/changesitemasterpage.aspx||Changes the master page for the site collection (must be called from the site collection url, not a subweb url)|
|_layouts/permsetup.aspx||assings the 3 magic groups to a sharepoint web called from a web or subweb url|
|_catalogs/lt/Forms/AllItems.aspx||List template Gallery|
|_catalogs/solutions/Forms/AllItems.aspx||Site Template (/Solutions) Gallery|
|_layouts/user.aspx||A list of all groups and users in a given Site|
|_layouts/groups.aspx||A list of all groups in a given Site Collection|
|_layouts/AreaTemplateSettings.aspx||This screen chooses what site templates are available when creating a new site in a given site collection|
|_layouts/quiklnch.aspx||An almost odd list view of the quick launch items –
but not the one you get to from site settings.
This is linked to from the “getting started” web part.
|_layouts/qlreord.aspx||Same as above – this one lets you sort the quick launch items.|
|_layouts/AdminRecycleBin.aspx||End User Recycle Bin.|
|_layouts/AdminRecycleBin.aspx?View=2||Deleted from End User Recycle Bin.|
|Pagename.aspx?contents=1||View the web parts on a page – good for times when a web part keeps a page from rendering in normal mode.|