Hello Neo,
Here are some thoughts on improving forums.(but not sure from coding perspective side)
i- This is PRIORITY one for me and I think you will too agree on it. As already discussed let us allow guest posting with maximum level of checks to avoid spams. By this definitely more questions will come by which more users will start visiting the site and then more ideas will come over here.
ii- Let us increase number of levels of members status, currently we have:
1- ADMIN
2- MODs
3- Forums Advisers
We could add some more levels eg-->
4- Beginner(less than 20 posts or so)
5- experience(may be if someone crosses 100 posts)
iii- Let us give certificates for becoming forum adviser, MODs, admin or if any new levels we are creating to show that how valuable our site's awards are.
iv- We could have a dashboard kind of system where let us start award system like:
1- "Monthly/Yearly hero for asking questions"
2- "Monthly/yearly hero for answering"
3- "Monthly/yearly hero for editing/moderating posts."
4- We could take inspiration from SO a bit and could start badge systems for TAGs?(I leave this open for discussion with all here and we could have our own badges NOT copied from some other forums etc but more badges will definitely give KICK to users to involve more, we should take this also as a priority IMHO)
v- One more thought but that is more like question to all members how could we invite experts of new technologies too in here for new TAGS? by which we will definitely attract more visitors as well as we all will do learning too.
vi- Let us have a sub-forum where people share their experience and design may be or thoughts(only technical not like what's your mind) so that new comers can learn about projects, how about this?
vii- We could have meetings on TOLL FREE number or on skype etc? where we all could join monthly once(MODs, Forum advisers, admins) to discuss topics like this related to forums?
On another note: Can we have a NON-PROD environment for this site where if anyone interested could raise hand and try to learn and help you to reduce your over weight 
May be people could come up with more ideas on enhancement of forums and could apply them in first non-live site or a sub-forum and then could make them LIVE later?
EDIT: On your note of unix and shell technologies, I believe they are EVERGREEN languages may come and go but shell commands, shell scripting will always be there(with enhanced features I believe always) and people will be keep using it too, we need to only tell more and more people that we too have good platform(which many of them know but we have to publicize more now our forums) here where they could contribute on asking or answering questions rest will happen automatically. I tested it on many systems and on many times when ever I was searching for any UNIX related questions around 3 to 4 years back always OUR FORUM's replies it showed on TOP but now it shows on 3rd or 4th number so not sure how it works but if we make google also search our site as first answer then also we may get more visitors and active users IMHO.
Also BTW you yourself is a PHP expert(though I know you are a full busy guy handling alone a great site, but when you get sometime I mean here) how about teaching/guiding(by posting some good stuff on forums etc) us PHP and I know at least 20 people(from my college itself) who could ask thousands of questions on it itself
Thanks,
R. Singh