Who logs in the most?

I work in a firm with 10s of 1000s of Linux servers. A colleague had been emailed a list of servers and was trying to find out who owned them. At first, I suggested running last to see who last logged in but we realised this probably wasn't the best way to start the hunt. On reflection, the was a high chance that the user who logged in the most frequently into the server, was the the owner of that server. Or if not, he would most likely know the owner ;-)

So I used this 30 second one liner (wrapped for viewability) to list most frequent users:

 1$ last | perl -lane '$users{$F[0]}++; END { 
 2foreach $u (reverse sort { $users{$a} <=> $users{b} } keys %users) 
 3{ print "$u logged in $users{$u} times"; } }'
 4tom logged in 108 times
 5sally logged in 81 times
 6dave logged in 32 times
 7root logged in 27 times
 8richard logged in 8 times
 9admin logged in 3 times
10wtmp logged in 1 times