Use [dde] to get the page that the browser is on:

Must catch all dde requests, because they can fail (noticed with Opera 7.5 when looking at Transfers Window or when a page is loading)

  % dde request Mozilla WWW_GetWindowInfo 1
  "http://docs.iplanet.com/docs/manuals/communicator/DDE/index.htm","DDE Index",""

  % dde request FireFox WWW_GetWindowInfo 1
  "http://www.gigablast.com/","Gigablast",""

  % dde request IExplore WWW_GetWindowInfo 1
  "http://www.google.com","Google"
  Notice that iexplore only returns two results.

  % dde request Opera WWW_GetWindowInfo 0xFFFFFFFF
  "http://groups.google.com/groups?hl=en&lr=&q=dde+www_getwindowinfo&btnG=Search","Opera - [Google Search: dde www_getwindowinfo ]"

Notice that opera requires a different invocation.
Notice that the second result is "Opera - [INFO HERE]"  so you must parse out INFO HERE
Notice that opera only returns two results.