Using AppleScript to grab the URL from the frontmost window in web browsers: The definitive list

tell application "Safari"
    return URL of front document as string
end tell

tell application "Firefox"
    set myFirefox to properties of front window as list
    return item 3 of myFirefox
end tell

tell application "Firefox" to activate

tell application "Firefox" to activate
tell application "System Events"
    keystroke "l" using command down
    keystroke "c" using command down
end tell

tell application "Firefox" to activate

tell application "Firefox"
 if (front window) exists then do_something()
end tell

tell application "System Events"
 tell process "Firefox"
  set frontmost to true
  set xsist to (front window) exists
  (* keep xsist value to test later on *)
 end tell
end tell

tell application "Camino"
    return URL of current tab of front browser window as text
end tell

tell application "Firefox"
    set myURL to «class curl» of window 1
    return myURL
end tell

tell application "Camino"
    set p to properties of front tab of front window
    return |currentURI| of p as string
end tell

tell application "OmniWeb"
    set myInfo to GetWindowInfo
    return item 1 of myInfo
end tell

tell application "Opera"
    return URL of front document as string
end tell

tell application "Flock"
    set p to properties of front window as list
    return item 3 of p
end tell

tell application "Google Chrome"
     get URL of active tab of window 1
   end tell