Soft-link all files/directories from current path into `~/Library/Application Support`. I used this some time ago to keep settings under revision management and, by extension, synched between multiple Mac OS X machines.

link_AppSupport.sh

#!/bin/sh

DEBUG="yes"
filename="INIT_NO_FILE"
TODIR="$HOME/Library/Application Support"
FROMDIR="`pwd`"

# Functions
debugmessage() {
  test $DEBUG = yes &&
  echo "`date +%H:%M:%S` #DEBUG: $filename: $1"
}

linkit() { 
   ln -si "$FROMDIR/$filename" "$TODIR/$filename" &&
   echo "OK:  $filename: Link created." ||
   echo "ERR: $filename: Link *NOT* created."
}

# Main program
debugmessage "Started, DEBUG output enabled"
debugmessage "Traversing list of all files."
if [ $FROMDIR = $HOME ] ; then
  debugmessage "Checking if the current directory is plausible."
  echo "Directory not plausible ($FROMDIR), cancelling."
  exit 1
fi
debugmessage "Get the list of all files"
for filename in `echo "[A-Z]*"` 
do
  if [ -L "$TODIR/$filename" ] ; then
    debugmessage "This is a link."
    ls -l "$TODIR/$filename" | grep $FROMDIR >/dev/null
    if [ $? = 0 ] ; then
      debugmessage "Everything seems fine."
    else
      debugmessage "This link does not belong to us"
      echo "ERR: $filename: Strange link target?"
    fi
	else
	  debugmessage "No link exists."
    if [ -e "$TODIR/$filename" ] ; then
      debugmessage "Exists but it is not a link. Checking with diff..."
      diff -qr "$TODIR/$filename" "$FROMDIR/$filename" >/dev/null
      if [ $? = 0 ] ; then
        debugmessage "The files are identical (according to diff -rq), trying to remove one of them."
        echo "$FROMDIR/$filename and $TODIR/$filename seem identical, remove the one existing in $TODIR?"
        rm -ird "$TODIR/$filename"
        if [ $? = 0 ] ; then
          debugmessage "File was removed, creating link..."
          linkit
        else
          debugmessage "Unable to remove file!"
          echo "ERR: $TODIR/$filename: Please remove manually." 
        fi
      else
        debugmessage "Files differ, human attention needed."
        echo "ERR: $filename: You need to cleanup manually."
      fi
    else
      debugmessage "File does not exist, creating link..."
        linkit
    fi
  fi
done
filename=END_NO_FILE
debugmessage "FINISHED."