$::variable works too...
@::variable or
%::variable depending on what you're trying to access

(Rather useless unless you're planning to do some obfuscation ;-)

Furthermore I reommend the camel book (chapter 5) to understand why %main::main::main::variable works and is similar to %::variable or %main::main::main::main::main::main::variable (add as many main:: as you want before variable)