I learned a great deal about Photoshop from joining a forum on it. Actually, I joined an association, the NAPP (National Association of Photoshop Professionals) based, in the US. One of NAPP's leading lights is Scott Kelby, the worlds most successful author of computer-related books. Their forum, which is devoted to all things Photoshop, Lightroom and digital photography, generally, is full of people who are often working as professional graphic designers and photographers, and very skilled at using the tools of their trade. So, if you ask them a question - usually - those who know really know the answer will respond and those who don't will either not reply or say "I'm not the best one to ask about this - but you could try this or that".
I feel very safe in that forum, and my personal knowledge of Photoshop and especially Lightroom (my personal favourite digital photography software) has increased ten-fold in the few years I've been asking questions there (and now, I even offer advice - especially about digital photography).
Another excellent forum - technically speaking it's an email list - is Prodig. It was the brainchild of professional photographers Ed Horwich and Martin Evening (a hugely successful digital photographer and author) and is overseen by some of the most knowledgeable people in the digital imaging universe. Some big names in digial photography frequently respond to queries, and the amount of deadly accurate - and incredibly fast - help for a digital imaging problem, that can be gained from simply sending an email to that group is often nothing short of phenomenal. Although, I have to admit, a lot of the detailed technical information - and even the questions posed - can go right over my head.
One thing that those two groups have in common (and especially Prodig) is that subscribers generally use their own names to pose questions and offer solutions.
But there are other forums that are simply more trouble than they are worth. Too much of the time, the members hide behind psuedonyms like: "Flying Fish", "Mary's Dad", "ProPhotos" and "ShutterCrazy" - all meaningless but a false name allows those hiding behind it to say what they like, without taking responsibility or "ownership" of their words.
They offer opinion disguised as expert advice, that is often misinformed and frequently downright wrong. The forum then becomes a playground for the one-eyed "expert" to lead the partially sighted beginner. The problem with that, is there are people out there, who don't know any better being lead up the digital garden path by people who haven't got the intelligence to know that what they are spouting is gibberish - nor the good grace to know when to keep their mouths tightly zipped.
For me, it's one of the major failings of the internet - and some would say one of it's major advantages. Anyone can say whatever they like about whatever they want. But, please, if you're doing it on a forum where others might actually action your ideas - at least have the guts to sign your name to it. At least then, you might start to take some responsibility for what you write.