Pale Moon is a web browser derived from Firefox. It's not just a repackaged variant, but progresses with its own XUL-based interface focused on ease of use, but still incorporates latest Firefox technologies and supports many browser extensions.
K-Meleon is an extremely fast, customizable, lightweight web browser for Windows. It's based on Mozillas Gecko layout engine (like Firefox). It provides a classic tabbed browser interface with lots of customization options.