libwpd is a library designed to help process WordPerfect documents. It exposes a simple callback-based API (similar to SAX), allowing it to be easily plugged into any C or C++ application. It is used by recent versions of AbiWord and OpenOffice.org to provide WordPerfect file import.
Pathfinder provides a mechanism for any program to perform RFC3280-compliant path validation of X509 certificates, even when some of the intermediate certificates are not present on the local machine. It will automatically download any such certificates and their CRLs from the Internet as needed using the AIA and CRL distribution point extensions of the certificates it is processing. By default, the Pathfinder daemon listens on the D-Bus system bus for incoming requests.
UniConf is a configuration system that includes all the others with plugin backends and frontends. It supports retrieving, storing, and enumerating key/value pairs (where both keys and values are strings), multiple backends where the actual key/value pairs are stored, multiple frontends for tying it to other configuration architectures, and notifications. Currently it has plugins for GConf, KConfig, SNMP, INI files, the Windows Registry, and MailDir, amongst an always growing list.
WvDial (pronounced "Weave Dial") is an easier way to connect to the internet. It completely avoids the need for chat scripts, edits pap-secrets and chap-secrets for you, detects your modem automatically, and chooses a valid init string. It can even read and respond to command prompts at almost any ISP.
WvStreams is a library set composed of a number of parts. Among them are WvIPStreams (WvTCPStream and WvUDPStream), WvStrings (yet another C++ String class), WvCrypto Streams (including an easy way to add SSL support to applications), UniConf (a universal configuration system), WvLog (nice, simple handling of log files), and a whole host of other goodness. These are the base classes used to build programs such as the ever popular WvDial, TunnelVision, FastForward, KWvDial, and retchmail.