wkhtmltoimage and wkhtmltopdf render HTML pages into PDF or convert them into image files respectively. They're utilizing the QT Webkit runtime for "headless" operation without a running browser or display server.
Fifth is a Linux-exclusive browser that carries the best features from Opera, as well as a few unique features that are likely to please Linux power users. It's based on a custom Webkit port to FLTK and comes licensed under the GPLv3.
Midori is a fast web browser, which still makes the latest HTML5/CSS3/JS5 features available through WebKit. It comes with a lean user interface per default, but is extensible per plugins or userscripts, integrates privacy and ad-blocking features, and is available cross-platform.
MDR displays unified diff output in a graphical window, highlights changes (new and removed parts) per highlighting. It can be combined with any source control system (it's somewhat like fossils builtin diff --tk, but for git, hg, bzr or svn). It runs on WebKitGtk.
kchmviewer is a viewer for Windows HTML compressed help (CHM) and Ebook (EPUB) files. It's either buildable as KDE application or standalone Qt program. It has broad support for internationalized charsets and help files.
Eilat provides a minimal Qt/WebKit-based browser window. It's written in Python and primarily provides keyboard interaction. It's focused on security and privacy by isolating web site instances and avoiding a cache, persistent cookie storage, but logs actually retrieved network resources. It provides limited bookmarking, but no file download support.