I much like:

use Cwd qw(realpath);
use File::Basename;

my ($BIN, $BINPATH);
BEGIN { $BIN = basename($0); $BINPATH = realpath($0) }
[download]

over FindBin.

We simply take $BIN = basename($0) to ensure wrapper scripts work well. Often, $0 is symlinked to the actual executable -- we'd like to refer to the base filename as the basename of the symlink path, not the basename of the actual resolved $BINPATH.