We built a custom plugin for Atlassian Answers to do this. It's not open source and we haven't thought about making it available to customers at this point (it's got a lot of Answers-specific stuff hard-coded in it).
The "Featured Topics" section is the equivalent experience provided out-of-the-box by Confluence Questions.
If you have feature feedback for Confluence Questions, you can create suggestions in the JIRA project: https://jira.atlassian.com/browse/CQ
Do you use templates with Confluence? Take part in a remote 1-hr workshop. You'll receive USD $100 for your time! We're looking for people to participate in a remote 1-hr workshop...
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