Syntax
      DIR [pathname(s)] [display_format] [file_attributes] [sorted] [time] [options]

Key
   [pathname] The drive, folder, and/or files to display, 
              this can include wildcards:

                 *   Match any characters
                 ?   Match any ONE character

   [display_format]
                /P   Pause after each screen of data.
                /W   Wide List format, sorted horizontally.
                /D   Wide List format, sorted by vertical column.

   [file_attributes] /A: 

   /A:D  Folder         /A:-D  NOT Folder
   /A:R  Read-only      /A:-R  NOT Read-only 
   /A:H  Hidden         /A:-H  NOT Hidden
   /A:A  Archive        /A:-A  NOT Archive
   /A    Show all files
   several attributes may be combined e.g. /A:HD-R

   [sorted]   Sorted by /O:

   /O:N   Name                  /O:-N   Name
   /O:S   file Size             /O:-S   file Size
   /O:E   file Extension        /O:-E   file Extension
   /O:D   Date & time           /O:-D   Date & time
   /O:G   Group folders first   /O:-G   Group folders last
   several attributes may be combined e.g. /O:GEN

   [time] /T:  the time field to display & use for sorting

   /T:C   Creation
   /T:A   Last Access
   /T:W   Last Written (default)

   [options]
   /S     include all subfolders.
   /R     Display alternate data streams. (Vista only)
   /B     Bare format (no heading, file sizes or summary).
   /L     use Lowercase.
   /Q     Display the owner of the file.

   /N     long list format where filenames are on the far right.
   /X     As for /N but with the short filenames included.

   /C     Include thousand separator in file sizes. 
   /-C    don't include thousand separator in file sizes.

   /4     Display four-digit years

The switches above may be preset by adding them to an environment variable called DIRCMD.
For example: SET DIRCMD=/O:N /S

Override any preset DIRCMD switches by prefixing the switch with -
For example:
DIR *.* /-S

Upper and Lower Case filenames:
Filenames longer than 8 characters - will always display the filename with mixed case as entered.
Filenames shorter than 8 characters - may display the filename in upper or lower case - this may vary from one client to another (registry setting)

To obtain a bare DIR format (no heading or footer info) but retain all the details, pipe the output of DIR into FIND, this assumes that your date separator is /

DIR c:\temp\*.* | FIND "/"

FOR /f "tokens=*" %%G IN ('dir c:\temp\*.* ^| find "/"') DO echo %%G

Normally DIR /b will return just the filename, however when displaying subfolders with DIR /b /s the command will return a full pathname.

Checking filesize during a download (to monitor progress of a large download)

   TYPE file_being_downloaded >NUL 
   DIR file_being_downloaded

Since TYPE won't lock the file_being_downloaded in any way, this doesn't pose a threat to the download itself.