For the last few months I'm building a community platform based on Drupal 8 (the work is still in progress). Although it's a great (or better the) resource to find information about Drupal, In my opinion some important features are still missing..
A step into the right direction: the user's starred list
In the last year there was a awesome improvement called the starred list available on the user's profile. A user is able to bookmark different kind of content (e.g. a module's profile page or a page of the Drupal documentation). Then all the bookmarked content is listed on a view. This small feature helps shortening the research time in an enormous way, when you are searching the needle in a hay stack .
One thing here I really would like to see is, that the list is searchable.
Wish list feature number one: up and down voting widget on project pages
To get a faster insight, we should implement a up and down voting widget.
Wish list feature number two: donate to the developer widget
For those people who are'nt able to contribute back to Drupal, because they are not able to code patches, we should establish a widget where they can donate money to the developer directly. This is in my opinion one more incentive for developers to force development of a module. Of course donating money should always happen on voluntarily base.
Wish list feature number three: Drupal best practices/how-to's/cookbook
Although Drupal.org is a great information source already, it's often quite difficult to find some information. In my opinion there should be a separate documentation, how to solve different use cases. It should include what modules should be used, and how they play together.
For example: "How to sell site access via user roles"
Drupal is great (as already mentioned) as the information source for Drupal, but over the years I invested hours to find what I'm searching for. Especially for beginners is even more difficult to dive in into the Drupal the universe.
We should get inspired by websites like drupal.stackexchange.com or drupalize.me to provide a better usability and user experience on drupal.org.
We should never forget, that the beginners of today may be the developers of tomorrow. So it should be our all intention, to make Drupal.org as much as possible to easy to use.