How to maintain an emacs-based knowledge base?

[org-mode] is great for managing somewhat 'actionable' items, but I keep adding things of a more general nature, that I won't be needing on a day-to-day basis (how-tos, reading notes etc), so it's getting slow and hard to manage.

I'm a follower of David Allen and his Getting Things Done methodology. I'm using Emacs for three of the lists he recommends:

• Next Actions

• Project Resources

• The Someday/Maybe list

The material I'm concerning myself with doesn't fit the /projects/tasks/sub-tasks paradigms, they are more like little knowledge nuggets on selected topics, which are inherently more complex to classify and manage.

I've been wondering what kind of structure could be used to handle that kind of information (classification and retrieval), and if there are maybe other modes that could help with the job ?

For this kind of information I've migrated away from emacs. Instead I keep a directory ~/etc/howto, and in that directory I put files that contain "little knowledge nuggets on selected topics", where the key criterion is that the information has long-term value.

I could search this directory with Emacs, but my Emacs Lisp is not so hot, so I wrote a howto shell script instead (some error checking omitted for clarity):

case $# in
  1) ;;
  *) echo "Usage: $0 <topic>" 1>&2; exit 2 ;;
esac

topic="$1"

# Note the ordering: first exact matches, then beginning matches, then any matches

set xxx `find $HOME/etc/howto/. -name "$topic"     -not -type d -print` \
        `find $HOME/etc/howto/. -name "${topic}?*" -not -type d -not -name '*~' -print` \
        `find $HOME/etc/howto/. -name "?*$topic*"  -not -type d -not -name '*~' -print`
shift

case $# in
  0) echo "No file found matching