Should I avoid "linking to" or promoting other websites. Especially those that utilize advertising that may compete with StackExchange's advertising. Thus far I have avoided answering questions that request help in finding an application to complete a project. The FAQ section "May I promote products or websites I am affiliated with here?" discusses self promotion. I am referring to websites that offer free or payed downloads and utilize heavy advertisement on their site. Though I have no affiliation with them I have always been concerned that "linking to" or promoting these other websites may be frowned upon. Am I right to avoid linking to these sites, or am I being over cautious?
As I said in my first comment, "link only answers" are bad (even if the link is valid). Links should be given as reference but the suggested solution should also appear in the post.
That being said, I think you might be overthinking the situation. If you would like to share a useful resource while answering someone else's post, then go right ahead. The fact that that resource might be behind a "pay wall" has nothing to do with the possible validity of the solution they offer. If there is a "free" alternative, try to include a link to that as well - I'm pretty sure that would go down quite nicely with all the users involved :)
It should not interest you what advertising is implemented on the site you are linking to (unless of course it was an SE hate speech site ;) In all seriousness and IMO, I don't think you have to worry too much about posting links to outside resources as long as your actual post contains enough information to stand on its own without the link.
In my own experience, I don't like leaving Stack Overflow in order to get more information about a problem. Personally I think jsFiddle is great - but I hate it when a question is posted with no code, only an explanation and a link to jsFiddle...
I always try to include as much info as I can about the link, so that people will only need to click the link if they want to know more - not to find out what it is, because I made sure to already clearly state the contents of the link.
If your answer is going to be something like
There is a site that does this, you can find it here.
Then yes, refrain from posting it. It will certainly attract down-votes and it might be removed as spam.
If instead, you elaborate an answer and you also link like "check here for more info", then it's perfectly fine and actually it's a very good answer. :)
No. Link any and everything you want. All things accounted for, you aren't the SE team - as a matter of fact you are a consumer of their product. So you shouldn't/can't try and think of yourself as if you had SE's best interests at heart (as a corporation) - because you probably don't, and that's normal. I don't think very many people here do. I'm just here participate/learn/troll in so far as it's fun for me
Experts-Exchange is now taking a (surprisingly) hard line on this.
From the Sept 11 EE newsletter
Linking to off-site content
The hurts more than it helps link:
These are the ones to competing Q&A sites (as opposed to a MSDN page). Even if the comment quotes from the page, the link will be removed.