DeuTex is a WAD composer for Doom, Heretic, Hexen, and Strife.  It can be used
to extract the lumps of a WAD and save them as individual files.  Conversely,
it can also build a WAD from separate files.  When extracting a lump to a
file, it does not just copy the raw data, it converts it to an appropriate
format (such as PPM for graphics, Sun audio for samples, etc.).  Conversely,
when it reads files for inclusion in PWADs, it does the necessary conversions
(for example, from PPM to Doom picture format).  In addition, DeuTex has
functions such as merging WADs, etc.  If you're doing any WAD hacking beyond
level editing, DeuTex is a must.

WWW: http://www.teaser.fr/~amajorel/deutex/