Poor man's referrer log

Looking for real-time feedback as to where Web traffic is coming from, but don't want to deal with the overhead of writing to a database or text file on every request like Refer and ShortStat?

Here's a simple PHP script I use to grab the most recent referrers from Apache's logs:

<?php

$refs =
  `tail -5000 /var/log/apache/centricle.com/access.log \
        | cut -d '"' -f 4 \
        | grep -v '^-\|http://\(www.\)\?centricle' \
        | tac`;

echo "<pre>$refs</pre>";

?>

For those who don't spend much time on the command line, here's a quick explanation of what's happening:

tail grabs the last 5000 lines from access.log, and hands them off to cut, which finds the 4th field (as delimited by a double quote), and feeds it to grep. If that field doesn't begin with a single dash (-), 'http://centricle', or 'http://www.centricle', it's added to a list that's passed to tac, which prints the list in reverse.