I understand why it might be useful, but I don't think that there needs to be an overall set of links.

The tag and tag wiki features allow that information to provided at the specific level it is needed. Anyone can create tags and edit their wikis. Depending on rep, the edit may be subject to approval.

For example, there is an [tag:apex] tag wiki (https://salesforce.stackexchange.com/tags/apex/info) that does have links to external sources such as the Apex Developer's Guide.

There's no tag hierarchy, but an undocumented-feature tag along with something more specific like url-hacking might not be bad. It'd be similar to how there is a general apex tag and many questions that are tagged with it are also tagged with more specific tags. 

I could also see community wiki Q&A's for stuff like top learning sites, etc. Like this [Getting Started with Haskell][2].

So, I think that the combination of tag wikis and community wikis can work.

[1]: https://salesforce.stackexchange.com/help/on-topic
[2]: http://stackoverflow.com/questions/1012573/getting-started-with-haskell/1016986#1016986