The reason my window manager is called "AHWM" is because all the good names are taken. In order to reduce your googling, this is a list of window manager names that take the form "?wm" where "?" is a letter. Note that most of the letters are taken and a few have been used more than once. Also note that the following names are free: 2wm, 3wm, 5wm, 6wm, 7wm, 8wm, 0wm (1wm, 4wm and 9wm are taken).

Also of interest might be my table of two letter Unix commands.

Summary:

• Open: ewm, fwm, qwm.
• Possibly open: bwm, cwm, owm, rwm, ywm, zwm.

The List:

• awm: Ardent Window Manager
  http://www.plig.org/xwinman/others.html
  mentioned on plig website, can't find a web page.
• bwm: Boris's Window Manager [sic]
  http://www.advogato.org/person/bowis/diary.html?start=3
  Looks like just an idea, can't find any code.
• cwm: Cambridge Window Manager
  http://www.giccs.georgetown.edu/~ric/wm
  No code found, above site mentions it was "written at IBM (?) for X11R3."
• dwm: DESQview Window Manager
  This seems to have little to do with X, but I'd consider the name taken.
• ewm
  Seems open, might be confused with Enlightenment.
• fwm
  Seems open, often confused with fvwm.
• gwm: Generic Window Manager
  http://koala.ilog.fr/gwm
  Configurable Lisp-based window manager.
• hwm: Hummingbird Window Manager
  Old commercial window manager for Exceed X server. Would have used it myself, but it might be trademarked (although it seems long abandoned) and I think these guys have lawyers.
• iwm: Unknown abbreviation, Interviews Window Manager
  http://project.turithil.org/iwm
  http://www.giccs.georgetown.edu/~ric/wm
  Two separate window managers: one is someone's pet project, just like ahwm, the other is too old to find any information about it.
• jwm: Unknown abbreviation
  http://www.joerch.org/jws/faq.html
  Looks like someone's abandoned pet project.
• kwm: KDE Window Manager
  http://www.kde.org
  One of the premier window managers, actively developed.
• lwm: Lightweight Window Manager
  http://www.boognish.org.uk/enh/lwm
  Another personal project.
• mwm: Motif Window Manager
  http://www.plig.org/xwinman/mwm.html
  The window manager nobody uses but everyone supports (through Motif hints).
• nwm: NooTe Window Manager
  http://noote.multimania.com/Nwm
  Not an X11 window manager, one of those MS Windows things.
• owm: Open Window Manager
  http://catalog.com/hopkins/unix-haters/x-windows/i39l.html
  Not an X11 window manager, a prototype window manager for the ill-fated NeWS windowing system. Often confused with olwm.
• pwm: Unknown abbreviation
  http://www.students.tut.fi/~tuomov/pwm
  A personal project, looks very well-developed.
• qwm
  Seems unused. I'm sure someone will write the QT Window Manager any day now.
• rwm: Reality Window Manager
  http://wearcam.org/usenix98/node14.html
  Some theoretical 3D thing.
• swm: Small Window Manager, Solbourne Window Manager
  http://www.informatik.hu-berlin.de/~sperling/prog/swm.html
  http://www.giccs.georgetown.edu/~ric/wm
  The Small Window Manager fits in less than 20K of disk, the other one was for X11R4.
• twm: Tom's Window Manager, Tab Window Manager
  http://www.plig.org/xwinman/vtwm.html
  The original twm.
• uwm: Ultrix Window Manager, Universal Window Manager
  http://www.giccs.georgetown.edu/~ric/wm
  http://www.plig.org/xwinman/others.html
  Can't find any information about either of these.
• vwm: Virtual Window Manager
  Some Litestep thing, might not even be an actual window manager.
• wwm: Weird Window Manager
  http://www.joerch.org/wwm
  Someone's pet project.
• xwm: X Window Manager
  Did you actually think you could use this? Xwm was the original window manager for X10 and was the working title for ahwm before I found out xwm was taken.
• ywm: Y Window Manager
  http://aleph-0.dhs.org/ywindow
  Someone is writing the Y Window System, and this is the window manager.
• zwm: Unknown abbreviation
  http://www.roard.com/zwm.html
  Abandoned project written in QT, built on an early version of kwin (KDE's window manager) before kwin became as good as it is today.