This is what i have been using for quite some time.
on $*:TEXT:/(www\.|http\x3A\x2F\x2F)([^\s]+)/iS:#: {
if (!$window(@links)) { .window -n @links }
.window -g2 @links
.aline @links $+($timestamp,) $+(14,$nick) $+(06,$chr(124),14) $chan $+(06,$chr(124),14) $1-
}
Its matches all links where they are prefixed with http://www. or just www.