The following are just a very few of the handy modules you can find at CPAN (Comprehensive Perl Archive Network, http://www.cpan.org/.). It represents just the tip of the iceberg. Additionally, CPAN does not contain all the handy Perl modules. Many are available other places on the 'net. And of course, Python and other languages have their own handy modules.
 

Netscape::Bookmarks	parse, manipulate, or create Netscape Bookmarks files
Netscape::History	Object class for accessing Netscape history database
AltaVista::SearchSDK	Perl extension for AltaVista Search Software Development Kit. Think that might be valuable in certain situations?
DBI and DBD	Database interfaces for many databases, including Altera SQL Server, CSV files, DB2, Empress, MS SQLServer and Sybase, Informix, Informix SE 4.10, Ingres, Msql, Mysql, ODBC, Oracle, QBase, PCDOCS/Fulcrum SearchServer, Solid, Sybase, and XBase.
XBase	Read/write interface to XBase files
VCS::CVS	Interface to GNU's CVS
IO::	All sorts of wrappers for file and pipe I/O.
Log::	All sorts of logging functionality.
AtExit	atexit() function to register exit-callbacks
Callback	Define easy to use function callback objects
Archive::Tar	Read, write and manipulate tar files
Archive::Zip	Provide an interface to ZIP archive files.
Compress::	Interfaces to various compression, including Bzip2, LZO, Lev-Zimpel-Vogt, Info-Zip zlib. Note that some of these technologies may be patented -- please don't do anything illegal.
Convert::	Conversion to and from many formats, including ASN.1, BER messages (can you say SNMP?), Mac BinHex, ASCII to/from EBCDIC, scientific notation numeric conversion, multi character set conversions, and UUencode and UUdecode
File::	Many, many functionalities including return basename of a filename, csh-compatible filename globbing, Check file/dir tree against a specification, Symbolic chmod, File compare, Copying files or filehandles, Persistent counter class, Free disk space utilities, Call func for every item in a directory tree, Auto-create locks, Parse directory listings, File locking using flock() and lockf(), Interface to lockf system call, File path and name utilities, Read/write/append files quickly, Emulate some functions of sort(1), Handling files and directories portably,  A by-name interface for the stat function, POSIX/*nix fsync() and sync(), A more efficient tail -f.
Filesys::	Includes  Disk free based on Filesys::Statvfs, OS independant parser of the df command, Interface to the statvfs() system call, and Translate mode 0644 to -rw-r--r--.
Algorithm::	Diff (also Longest Common Subsequence), Knuth's sample algorithm, Knuth's shuffle algorithm, Handy and fast permutation with object oriented interface.
Array::	Comparing arrays, handling arrays using IntSpan techniques, and print elements in vertically sorted columns (think this might be nice for quick reports?)
Bit::Vector	Efficient bit vector and set base class
Class::	This is for those guys who truly think OOP. Includes: Accessor - Automated accessor generation, BlackHole - Base class to treat unhandled method calls as no-ops, Classless - framework for classless OOP, Contract - Design-by-Contract OO in Perl., DBI - imple Object Persistance, Fields - Inspect the fields of a class, Handler - Create Apache-like pseudoclass event handler, ISA - report the search path for a class's ISA tree, MethodMaker - a module for creating generic methods, Multimethods - Support multimethods and function overloading in Perl, Mutator - Dynamic polymorphism inplemented in Perl, NamedParms - A lightweight named parameter handling system, ParamParser - Perl module that provides complex parameter list parsing, ParmList - A collection of routines for processing named parameter lists for method calls, Singleton - Implementation of a "Singleton" class, Template - Struct/member template builder, Translucent - A base class for translucency, Tree - C++ class hierarchies & disk directories, Whitehole - base class to treat unhandled method calls as errors.
Data::DRef Data::Dumper Data::Flow Data::Locations Data::Reporter	Nested data access using delimited strings Convert data structure into perl code Acquire data based on recipes Handles nested insertion points in your data Ascii Report Generator
Date::	Gregorian calendar date calculations, Conversion between Gregorian, Hebrew, more?

Decision::Markov	Build/evaluate Markov models for decisions. I don't know what this is, but it sure sounds interesting.
DFA::	Discrete Finite Automata command processor and an "augmented transition network". Can you say Comp Sci?
Heap::	For you guys who want to implement your own heap in Perl.
Math::	It's a rare programmer who knows enough math to use everything in this set of modules. Includes all sorts of stuff, simple, complex, and even obscure. If it involves math or numbers, look here.
Object::Interface Object::Transaction	Allows specification of an abstract base class Virtual base class for transactions on files containing serialized hash objects (say what?)
Persistent::	An Abstract Persistent Base Class, an Abstract Persistent Class implemented using a DBI Data Source, and persistent classes implemented using a LDAP Directory, a mSQL database, a MySQL database, a Sybase database, and an Oracle database.
Set::Bag Set::IntRange Set::IntSpan Set::Object Set::Scalar Set::Window	bag (multiset) class Set of integers (arbitrary intervals, fast) Set of integers newsrc style '1,5-9,11' etc Set of Objects (smalltalkish: IdentitySet) JLLEROY Set of scalars (inc references) Manages an interval on the integer line
Sort::ArbBiLex Sort::Fields Sort::PolySort Sort::Versions	make sort functions for arbitrary sort orders Sort lines containing delimited fields general rules-based sorting of lists sorting of revision (and similar) numbers
Statistics::	If your assignment involves statistical analysis, use this stuff to substitute for your missing Statistics expertise.
Chart::Base Chart::GnuPlot Chart::Graph Chart::Pie Chart::Plot Chart::XMGR	Business chart widget collection Access to gnuplot library front-end to gnuplot and XRT Implements "new Chart::Pie()" Graph two-dimensional data (uses GD.pm) interface to XMGR plotting package
GD	GIF editing/painting/manipulation
GIFgraph	Package to generate GIF graphs, uses GD.pm
Gimp	Rich interface to write plugins for The Gimp
Graphics::Libplot Graphics::Simple	Binding for C libplotter plotting library Simple drawing primitives
Image::Grab Image::Magick Image::Size	Grabbing images off the Internet Read, query, transform, and write images Measure size of images in common formats
MPEG::MP3Info	Extract/edit tag information in MP3 files
OpenGL	Interface to OpenGL drawing/imaging library
PGPLOT	scientific graphs