seems this is the third or fourth post i've seen on one-liners recently, but i've found another of my favorite uses for them - testing object methods. it's a pretty simple thing, really:
perl -MMyModule -MData::Dumper -e '$foo = MyModule->new(); print Dumpe
and that's it.
but this way i can verify that objects are instantiated correctly, and add whatever quicky method calls ( like one set of objects that uses another method to fetch DB records ).
quick, easy, and also good to use with the Devel::DProf to scan for any intial problem areas without creating extra test scripts.