Also, what do you do if the lyrics site doesn't have the song? Does WWW::Mechanize complain?

Here are a few pointers:

If you're going to do a substr() on a scalar and save the result into another scalar, you don't need to explicity copy the scalar first. You can just do:

my $firstletter = substr($artistsong,0,1);

Also, for translating something entirely to capitals, perl has a builtin:

$songtitle = uc $songtitle;