Recs.
Updated
Bug.n is a tiling window manager for Microsoft Windows that is heavily inspired by DWM for Linux.
SpecsUpdate
Pros
Pro Customizable through config files
Just like DWM, bug.n is configured through a plain text file. This is a great resource for setting up your configuration. Original link is down, try this one for the Archive.org copy.
Pro Saves a lot of windows space
Bug.n can increase the available screen estate by freeing up the space occupied by
the Microsoft Windows Taskbar & the title bar for every single window by hiding and replacing all with a single slim status bar.
The status bar shows the current config of your window setup & can also show system information like time, date and memory usage.
Pro Handy resource monitor
Has an own conky style resources monitor in its statusbar showing cpu/ram/disk reads/writes, network uploads/downloads and time.
Cons
Con Confusing at first
It is a great program but without a good tutorial. There are a lot of technical documents, which is interesting if there is first a basic tutorial to help the user start. To really understand this software there must be a knowledge of autohotkey. For those familiar with autoit and not autohotkey, there may be a learning curve.
Con Doesn't play well with Firefox
Mozilla Firefox has captions and titlebars (using Win-Shift-D (show/hide active titlebar) doesn't work in Mozilla windows) that don't play well, meaning they stay no matter how long one tries to remove them.