I use this one to clean my home directory of useless '.save*' files. This script goes through all occurances of such files in current and sub-directories. It then looks at whether the owner process (to which this temporary file belonged) exists and removes the temporary file no owner processes are found to be running at the moment.
I believe this is my second attempt at writing abfuscation ;-).
$"=q;grep;;$,=q"grep";for(`find . -name ".saves*~"`){s;$/;;;/(.*-(\d+)
+-.*)$/;$_=["ps -e -o pid | "," $2 | "," -v "," "];`@$_`?{print"+ $1"}
+:{print"- $1"}&&`rm $1`;print"\n";}