subtle is a grid-based manual tiling window manager with a strong focus on easy but customizable look and feel. In comparison to other tiling window managers, subtle has no automatic tiling of the screen size in any way. Instead, windows are arranged according to positions inside of a grid. These positions are called gravities.
i3 is a dynamic tiling window manager. Its key features are correct implementation of Xinerama (workspaces are assigned to virtual screens, and it does the right thing when attaching new monitors) and XrandR support (which is still unfinished). Both horizontal and vertical columns can be used in tiling. There is a special focus is on writing clean, readable, and well documented code. i3 uses xcb for asynchronous communication with X11, and has several measures to be very fast. i3 is primarily targeted at advanced users and developers.
Bluetile is a tiling window manager designed to integrate with the GNOME desktop environment. It provides both a traditional, stacking layout mode as well as tiling layouts where windows are arranged to use the entire screen without overlapping. Bluetile tries to make the tiling paradigm easily accessible to users coming from traditional window managers by drawing on known conventions and providing both mouse and keyboard access for all features.
x9wm is a clone or fork of the 9wm and w9wm X window managers. It is a light alternative for the Mac OS X desktop. All of its source code is contained in a single file. It supports an alterate red colored cursor. It is very light on resources, quite fast, very simple, and easy for long programming, editing, or Web work sessions. You can blend it with Nitrogen and Wbar to create a simple but elegant interface without iconic or stylistic clutter. It does not decorate windows with borders, and it is modal, controlled with the mouse.
Notion is a tiling tabbed window manager for X. This means the screen can be freely divided into tiles that contain the client windows. Multiple client windows can occupy the same tile; in that case they will be tabbed, much like browser tabs. This way, windows will not overlap and it becomes easier to manage your screen real estate. Its functionality can be configured and even extended with Lua scripts. Various scripts are available, such as for NetWM features and multihead support.
feed2wmmenu is a tool to generate X11 window manager menus from RSS, ATOM, or other news feeds. It was inspired by "fvwm-menu-headlines", which generates static refreshed FVWM menus from RSS or other kinds of news feeds. The drawback of the FVWM related script is the use of simple regular expressions. feed2wmmenu polls the feeds using curl, utilizing the Last-Modified header so that the feeds are potentially not fetched if they didn't change since the last poll. It produces diverse output formats by using corresponding XSLT stylesheets.