libircclient is a small but powerful library that implements the client-server IRC protocol. It is designed to be small, fast, portable, and compatible with RFC standards and most IRC clients. It includes multi-threading support, sync and async interfaces, CTCP and DCC support, and color support. Good documentation and examples are available.
kchmviewer is a CHM (Winhelp) files viewer written in Qt/ KDE. It can be build as a stand-alone Qt-based application or a KDE application. The main point is compatibility with non-English CHM files, including most international character sets. It has the features set of standard viewer: search (including non-English CHMs), bookmarking, font size changing, index/content browsing, codepage support, and more.