A committee hack is a member of a community who will tend to gravitate towards the organisational hub of said community. The progression from the outer to the inner organisational circles is a natural and often smooth transition, the end result of which (for better or worse) being that the individual will eventually assume one or more roles of responsibility for co-ordinating the community for a seriously silly period of time.
It is first important to note that all members of a community who end up taking part in the organisation of the group are not committee hacks per se.
This is because it is reasonable to assume that a person may end up taking the reins temporarily for any number of reasons, Brownian motion even being a feasible cause.
In the case of the authentic committee hack there are two significant attributes to check for which will give away the true identity of the individual under scrutiny:
They're Having Fun!
No matter how much they may protest, a true committee hack (deep down inside) really, really enjoys the act of participating in a committee-like structure and offering a guiding hand to the direction of the community.
Though they may protest the accusation and complain bitterly about the work they need to do in their role and the time required to do so, they will always return to the committee fold time and time again.
In some cases, if you are unsure, the perfect way to flush out a committee hack is to raise the possibility of placing a prominent individual with vastly different ideals in the current position of a suspected hack - if they are authentic the reaction will be (to say the least) like unto fire and brimstone. You may in fact want to try this trick from a flame-proof bunker or be very quick on your feet.
The reason that this trick works is that committee hacks are fiercely proud of their work and want the effects they have caused to stay tangible within a community for as long as possible (so long as they are good effects!) for the assumed fame and gratitude that will follow.
The other primary giveaway of a true committee hack is the sheer number of years that will be dedicated to the organisation of a community (or indeed several, a committee hack often has the talent to be drawn into several independent organisational epicentres simultaneously).
One of the most beneficial consequences of being an active committee hack is the experience it brings. Because a committee hack spends a good deal of time at the centre of a community taking on a wide variety of responsibilities, a vast amount of experience is gained - not only concerning the specific tasks undertaken but also (and far more valuable) in the areas of time and project management, interpersonal relationships and teamwork.
On the flipside, by taking on all of these responsibilities, life rapidly becomes extremely busy and often stressful for the committee hack. If skills in managing time and projects are not firmly in place, or rapidly acquired, the committee hack is likely to start burning out. The process of burning out may take any amount of time, depending largely on the type of person to whom it is happening. The ultimate conclusion of the burn-out is also varied - ranging between a final quiet resignation from committee life through to a tempestuous climax in which friendships and formal alliances alike are broken and the (now ex-) committee hack finds himself very much on the outside of the community.
For the Good or the Power
It is worth noting that the influence of a committee hack is not always a positive one - this comes down to some large extent to the primary drive of the committee hack in question.
When a person is driven primarily by the desire to enhance and extend a community, with little regard to the personal benefits (actual and/or perceived) of their actions the community is likely to benefit. Such a person will accept advice and constructive criticism and turn it to both their own and the community's advantage.
When a person is driven primarily by the desire for power (once again actual and/or perceived) matters are likely to take a turn for the worse. It is this sort of person who will aggressively pursue high-profile (and often important) roles and tasks only to let them slip and fail when they prove to be difficult or not universally popular. It is also far more likely that this sort of person will damage the community when they depart, far preferring for the community to bear the brunt of any failings they may have had rather than tarnish their public face.
The Sum Total
In the end, it is important to understand that a community with committee hacks will often benefit greatly if the hacks are capable, and will quite possibly languish and die if a 'bad hack' comes along, because they do make changes from the very core.
Of course, at the end of the day it's really only the committee hacks who notice each other - the bulk of a community will tend to exist maintaining a notion that their community will just 'continue continuing' without any particular work being done - and without these types of people the committee hacks wouldn't have groups to maintain (for there would be no work to be done in a community which realised that work needed to be done!).
So there it is - nurture your committee hacks and watch your community grow, but be sure that your hacks are capable lest your community grow into a turnip.