dvtm brings the concept of tiling window management, popularized by X11-window managers like dwm, to the console. As a console window manager, it tries to make it easy to work with multiple console based programs like vim, mutt, cmus, or irssi. dvtm is intended to be used where X11 isn't available or over SSH. In conjunction with dtach, it can be seen as a lightweight alternative to GNU screen.
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.
WMI is a lightweight window manager for X11 which attempts to combine the best features of larswm, ion, evilwm, and ratpoison into one window manager. It supports both the conventional way of managing windows in a overlapping manner and the screen-alike way of managing windows in a non-overlapping fashion.