Most useful options for git shortlog, using “Pro Git” book repo as an example.

Part of it:

git shortlog [<options>] [<revision range>] [[--] <path>...]

-n, --numbered
    Sort output according to the number of commits per author
    instead of author alphabetic order.

-s, --summary
    Suppress commit description and provide a commit count
    summary only.
           
    ... snip ...

<revision range>
    Show only commits in the specified revision range. When no
    <revision range> is specified, it defaults to HEAD (i.e.
    the whole history leading to the current commit).
    origin..HEAD specifies all the commits reachable from the
    current commit (i.e.  HEAD), but not from origin. For a
    complete list of ways to spell <revision range>, see the
    "Specifying Ranges" section of gitrevisions(7).

[--] <path>...
    Consider only commits that are enough to explain how the
    files that match the specified paths came to be.

Default output:

$ git shortlog
4wk- (1):
      4wk: ajusting the documentation - see #1053 and #1054

Adam Laflamme (1):
      - Fixed a typo in hooks.asc.  Issue #1169.

Adrien Ollier (42):
      removed and ignored Gemfile.lock
      added escaped quotation marks for git commit's message.
      added a new section for Git as a client for a Bazaar repository
      added a new section to import a Bazaar repository into a Git repository
      Modifications done as per Ben's suggestions.
      minor modifications
      removed trailing spaces
      ... snip ...

Sort according to contributions:

$ git shortlog -n
Ben Straub (803):
      Fix markdown H4's (convert into asciidoc H5's)
      Remove trailing spaces
      Add remaining headers to outline
      GitHub is a chapter
      Tweak github chapter
      Three trees
      Add some things
      Feedback
      ... snip ...

Just print a summary:

$ git shortlog -n -s 
   803  Ben Straub
   306  Scott Chacon
   105  Robert P. J. Day
    52  Jean-Noël Avila
    50  Cory Donnelly
    42  Adrien Ollier
    24  Kaartic Sivaraam
    20  Yue Lin Ho
    11  Markus KARG
    10  Kyrylo Yatsenko
    10  Sanders Kleinfeld
    ... snip ...

Don't count merge commits:

$ git shortlog -n -s --no-merges
   803  Ben Straub
   306  Scott Chacon
   105  Robert P. J. Day
    52  Jean-Noël Avila
    50  Cory Donnelly
    42  Adrien Ollier
    24  Kaartic Sivaraam
    20  Yue Lin Ho
    11  Markus KARG
    10  Kyrylo Yatsenko
    10  Sanders Kleinfeld
    ... snip ...

Restrict to a pathspec:

$ git shortlog -n -s --no-merges -- images
     5  Scott Chacon
     2  Adrien Ollier
     1  Ben Straub
     1  Duncan Dean
     1  Yunhai Luo
     $