I'm the original poster who suggested a clubs/partnerships section. There was a need for the clubs/partnership section for some important reasons.
First, there are almost no good, freely available internet resources for Partnerships/Clubs. There maybe be a handful of such ads on Trade a Plane, Barnstormers ,etc but this is extremely ineffective. No one really goes on those sites looking for Partnerships/Clubs because there's a paucity of ads and they are hard to search for. The only real place to find out about such opportunities are the Airport bulletin boards. While, quaint, I think we can do better than that.
Also, Partnerships/Clubs are highly geography specific. I would say this is even more important that aircraft type which people would normally search for. So it would make sense if these were separated from other adds in a manner that allows folks to browse by State.
On the other topic of subdividing the classifieds into sections, I think it's a good idea as long as we only use a few of major categories. For example:
Aircraft & Parts
Avionics & Handhelds
Clubs/Partnerships
Services