Never mind libwww-perl's GET, let's use the more well known wget:
$ wget -O file.txt
'http://en.wikipedia.org/w/index.php?title=Not_Dead_Yet&action=raw'
--2008-12-24 01:52:21--
http://en.wikipedia.org/w/index.php?title=Not_Dead_Yet&action=raw
Resolving
en.wikipedia.org... 208.80.152.2
Connecting to en.wikipedia.org|208.80.152.2|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1732 (1.7K) [text/x-wiki]
Saving to: `file.txt'
100%[======================================>] 1,732 --.-K/s in 0.04s
2008-12-24 01:52:22 (45.4 KB/s) - `file.txt' saved [1732/1732]
Anyway, your mission is to save URLs like the above into a file.