And in addition to the big stuff, don't forget the judicious use of Util modules.

Scalar::Util, List::Util, List::MoreUtil and Params::Util all provide a bunch of light, tight, fast things that make life a lot more livable.

For lazy testing so you can just dump tests in next to the code they are testing wherever you like, you might want to consider Test::Inline, although the original version (current production version) is not very lazy for more than one file, and the new Test::Inline 2.0 (which is FAR more lazy) is hovering at release candidates, and not production yet.