User:Ocotea is a signon that I use for lengthy cleanup efforts so that the watchlist for that signon doesn't become muddled with the watchlist for this one.
Warning to teachers and to would-be editors of technical content
In the English Wikipedia it is not possible in practice to stop technical content in the lead section of a page from degenerating into drivel with false statements in it, even if you keep it on your watchlist and keep a sharp eye on your watchlist. Since few readers go beyond the lead section, they will therefore be misled. It would be better not to create pages about technical subjects, but a lot have been created, and more continue to be created. Students need to be warned to disbelieve what they see here. The Wikipedia:NOTJOURNAL policy supports destruction of accuracy, and its antidote, the Wikipedia:Ignore all rules policy, is rarely effective in arguments on talk pages.
By "technical content" I am using the definition from WP:NOTJOURNAL as of 28 April 2015, namely any text that cannot be "written on the assumption that the reader will not or cannot follow [the] [hyper]links, instead attempting to infer their meaning from the text" where the reader is defined as "any literate reader of Wikipedia without any knowledge in the given field".
Although I have little experience in either, I think that Wikiquote and Wiktionary still value accuracy. Wikispecies is founded on the one-true-taxonomy philosophy and is thus no place for a biologist to venture.
The best advice I can offer for Wikipedia editors is that it is still possible to write accurate material that lasts on the talk page associated with each content page, perhaps under a heading such as "Don't believe what it says on the page". It should be possible to make a request to alter the Wikipedia:NOTJOURNAL policy, e.g. here, but these are dismissed as content disputes that don't belong on a talk page about policy.
Wikipedia has made me enthusiastic about using a pseudonym, a pseudonym that can have an extensive history attached to it, as this one now does, but which I've found from experience provides an important comfort factor compared to editing under my real name. Here, as elsewhere, there are people who are made uncomfortable by this, who complain that they can't have a discussion with someone whose genetic background they know nothing about, but I have no sympathy whatever for that point of view.
Professionally, I'm a systematic botanist, but I may edit in places that are unexpected even to me. In rough sequence from most to least editing effort (not necessarily number of edits), I usually work on:
I wish that people here were polite more of the time. Many editors that I've interacted with are wonderful, but too many are either trying to spoil the experience for others, or might as well be trying to because they are so rude.
I consider myself a content editor, interested in helping to build Wikipedia into an important educational resource, particularly for the large number of teachers who have few other resources. I rarely get involved in arguments unless there seems to be some way that I can settle them using research in published sources. I am likely to back away from pages that I would very much like to improve because somebody that I consider unreasonable has taken control of the page, but will fight back when I can see an effective and rational way to do so.
I would love to see an effective horde of scientists contributing here, but find that I completely agree with another editor whose essay warns academic people away from trying to do any good here. The same element that one encounters when teaching, people who attack you in unreasonable ways because you have knowledge (is it jealousy?), seems to be particularly common here. Knowledgeable people should be warned, but I hope that isn't completely discouraging, just a hint to go slowly and not expect unbounded success.
Editing Wikipedia can be personally rewarding. Some of us have discussed the way that Wikipedia can become part of one's personal filing system: adding interesting material here can be one of the most effective steps toward finding that information later when you want it. Humour department: the very first edit that I made in Wikipedia was because of the need to set a journal editor straight about a term that I'd used in a manuscript (I told him that I'd added the material with citations here).
Essential reading before venturing into Wikipedia editing: Shoggoth.
Ideas for a user box to helpfully indicate an editor's mental state, but that haven't yet reached the design stage:
This user is in an indefinable mental state, please edit my user talk page only after taking that fully into account.
This user has put up with just about as much inventive vandalism as any one person could possibly tolerate, and is likely to *big blot* the next vandal encountered.
This user is in a delicate mental state as a result of caring too much about wikipedia's long-term prospects of becoming useful.
People who delete sourced material because poor writing has given it an illogical spin. If you can't improve bad writing, you have no business deleting; there are templates available for tagging this sort of situation, see Template:Dubious, Template:Verify_source, Template:Failed verification. Once the citations have been deleted, they will not be retrieved from the page history.
People who merge pages on topics that have little logical connection just because they think one page or the other is too short.
Wikipedians who sneer at basic numeracy: the admin who claims that a person who has made two edits in the entire history of a page should be blocked for violating WP:3RR; the editor who claims that it is appropriate to put a tag on a page that says "This article is an orphan, as no other articles link to it.” when there are two incoming links, claiming that a minimum of three is required. So if 2≡3 and 2≡0, then 3≡0. In other words, we have all violated WP:3RR on any page that we have never edited, and we ought to be blocked. Very few, if any, of us should be allowed to remain. My retirement, and the retirements of many other editors are overdue (but we were well aware of that already).