A wonderful module that should be used in all code that deals with URIs and *must* be used in code that deals with URIs as entered by users or extracted from a document. I've seen too many problems in too much code that could be avoided simply by doing:
$uri_str = URI->new($uri_str)->canonical->as_string().
Bloom::Filter is a great implementation of a brilliant concept. It's fast enough to use in production settings with large datasets. You can store the object with Storable after adding items to it - and load it up anywhere for lookups.
Excellent sentence splitter - robust on poorly formed text and quite fast. I am processing gigabytes of data daily with this module.
This is the first XML module that makes me want to work with XML and related formats in Perl. It parses large documents in linear time as promised and provides a simple, yet incredibly powerful interface. XML::Twig is significant achievement - as almost everything else on CPAN for parsing XML goofs the performance / interface complexity trade-off. Highly recommended.