Libxml2 is the XML C library developed for the Gnome project. The library code is portable (to Linux, Unix, Windows, embedded systems, etc.) and modular; most of the extensions can be compiled out. Libxml2 implements a number of existing standards related to markup languages, including the XML standard, Namespaces in XML, XML Base, Relax NG, RFC 2396, XPath, XPointer, HTML4, XInclude, SGML Catalogs, and XML Catalogs. In most cases, libxml tries to implement the specifications in a relatively strict way. To some extent, it provides support for the following specifications, but doesn't claim to implement them: DOM, FTP client, HTTP client, and SAX2. Support for W3C XML Schemas is in progress. It includes xmllint, a command line XML validator.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
Libxslt is a C library for GNOME which allows developers to work with XSLT. It is based on libxml for XML parsing, tree manipulation, and XPath support. Also included is 'xsltproc', a command line XSLT processor. The library is written in plain C, making as few assumptions as possible, and sticking closely to ANSI C/POSIX for easy embedding. It should work on Linux, Unix, and Windows. Though not designed primarily with performances in mind, libxslt seems to be a relatively fast processor. It also include full support for the EXSLT set of extension functions as well as some common extensions present in other XSLT engines.
bitstring is a Python module that helps to make the creation and analysis of binary data as simple and natural as possible. Objects can be constructed from integers (big and little endian), floats, hex, octal, binary, byte data, iterables, or files. They can be sliced, joined, reversed, packed, unpacked, inserted into, overwritten, and otherwise operated upon with simple functions or slice notation. They can also be parsed, searched, and navigated in, similar to a file or stream. Internally the data is efficiently stored as byte arrays. It is available for Python 2.6 and later (including Python 3).
SQLObject is an object-relational mapper, i.e., a library that will wrap your database tables in Python classes and your rows in Python instances. It currently supports MySQL through the 'MySQLdb' package, PostgreSQL through the 'psycopg' package, SQLite, Firebird, MaxDB (SAP DB), MS SQL, and Sybase. It should support Python versions back to 2.4.
python-ldap provides an object-oriented API to access LDAP directory servers from Python programs. Mainly, it wraps the OpenLDAP 2.3+ libs for that purpose. Additionally, the package contains modules for other LDAP-related stuff (such as processing LDIF, LDAPURLs, and LDAPv3 schema).
Scapy is a powerful interactive packet manipulation tool, packet generator, network scanner, network discovery tool, and packet sniffer. It provides classes to interactively create packets or sets of packets, manipulate them, send them over the wire, sniff other packets from the wire, match answers and replies, and more. Interaction is provided by the Python interpreter, so Python programming structures can be used (such as variables, loops, and functions). Report modules are possible and easy to make. It is intended to do about the same things as ttlscan, nmap, hping, queso, p0f, xprobe, arping, arp-sk, arpspoof, firewalk, irpas, tethereal, tcpdump, etc.