Add urls to a list via Automator
This seems like an effective solution. A single Automator Run AppleScript action with the following script: 

set text item delimiters to linefeed
set my_list to "/Users/username/Documents/URL_list.txt"
tell application "Google_Chrome" to set new_items to (get the URL of the active tab in window 1) as string
do shell script "echo  " &amp; quoted form of new_items &amp; " &gt;&gt;  " &amp; quoted form of my_list

display dialog new_items with title "Added to the list"



Save as a service
Service receives selected URLs
Input is only URLs (probably doesn't matter)
Tested and working in both Safari and Google Chrome


If using Safari change the get the URL of the active tab in window 1 to get the URL of the current tab in window 1. Just to clarify: use active tab for Chrome and use current tab for Safari.
If you have several windows and tabs open and want to grab every URL to populate a list: tell application "Google_Chrome" to set new_items to (get the URL of the tabs in every window) as string