I use this section of code to identify www links:

Code:
  var %string = $1-, %islink = $false
  if ($regex(%string,/(www\.|http\:|\.com|\.net|\.org|irc\.|\/server)/i)) %islink = $true
  if ($regex(%string,/[aeo]wwww*\./ig)) %islink = $false
  if (%islink) echo -a This text contains a link.

Technically, it is for detecting spammers, but you should be able to modify it to suit your needs.

www links are harder to detect than email links because there isn't an easily identifiable character (@).

-genius_at_work