Okay, I’m in between status levels, as I know enough about the forum’s dynamics to understand most of what’s going on, but I do not yet consider myself a “vet”, so I’ll be the middle child that I am and try to bridge some of the gaps here.
First off, I agree that posting something knowledgeable is often a thankless job. It’s nice to know that you helped someone out, and I would hope that’s why any of us would appreciate a “thanks” - not to stroke our ego, but to know that we made a difference. I am guilty of not saying thanks enough, and I apologize for it. I guess I always assume that others know what good they’ve done me, but I guess they’re not clairvoyant. 
One source of this problem is that the violators (the ones not giving enough thanks) are often newbies, and either don’t stick around long enough to get an answer or don’t feel the need to respond since they got their quick fix.
While I am sure there have been some egregious instances of “thankless” posts (i.e. the pete example), there are also some reasons why thanks may not be given. In some instances, the poster may have just not checked back on their thread, which is shameful. In other instances, the less-experienced poster asking the question may not understand the answer. The poster may also be looking for more than one point of view on a question (in the case of the “anything else?” posts), as they may not be able to determine the helpfulness of the post they received.
Think if NeilG were the first to answer your question as a newbie. Should your answer be, “Golly gee, NeilG, I’ll eat everything raw from now on!”? The reason why someone is asking a question is because of a lack of knowledge, so we shouldn’t just assume that a poster will read our answer and take it for gospel, no matter how well thought-out it is.
Which brings me to another point. I know we all would like to assume that our logic is easy to follow and that we fully explain the reasoning behind our advice, but sometimes we don’t always get our ideas across well to newbies, especially those that don’t have a full grasp of the subject to begin with (thus, one of the reasons they’re "newbies). It’s very easy to blame a communication breakdown on the other person, but it is a two-way street.
Even considering all of this, I do agree that it is a shame how much valuable material is available here (measured both in time and money) and how little thanks the posters and T-mag get. Group hug.
Speaking of groups, a “social organization” has been mentioned. Yes, there are people who have been here a long time. Yes, they have formed at least e-lationships, which is cool. Yes, those in certain groups will respond to each other’s posts more often than those not in the group.
Are cliques a surprise? No. Are they a reason not to post a question? Definitely not. I’m sure all of us have seen a topic that we thought was important die a miserable death, while some stupid fish oil question (hahaha) got more play. One reason for this is that members of these “groups” know how to communicate with each other and also know each other’s background, so it’s more like a group of friends at a party discussing various topics. Compare that to the guy who walks into a party asking, “How 'bout them 'Canes!?!” While the discussion of the “'Canes” may be a valid one at that time, it would be much easier brought up once a dialog with others has been established. Same with these groups.
This is another area where your own communication skills or judgement of what’s important or relevant may be biased. This is not a full explanation of the behavior, but it’s another side of the story.
I now have a question for those of you that have mentioned that there is essentially “nothing new under the sun”. I completely agree that most, if not all topics seem to get stale. While there is no moral imperative to remain a part of an internet forum, I just wonder if any of you find your perfect diet and training plan and then never feel like changing. Things grew stale for me after a year or two here, but now that I’ve decided to switch to Westside, things are much more interesting.
I just feel that our body of diet and training knowledge keeps advancing with science and experience, so shutting the door on a lot of useful current information seems a little close-minded, but as long as we’re all striving for progress, it’s all good.
Demo Dick’s response was the highlight of