I imagine something that allows users to set some criteria :
Form logical and question types tags should be directly taken from and link to the docs.
The example I have in mind is the wordpress multi-criteria theme search page : https://wordpress.com/themes
The Discourse's docs page should do the work (3 criteria : category, tags and text search) but I don't know are flexible it is if you imagine it within the actual forum (there should be no difficulty with a dedicated discourse except to rebuild a community around it)
I am not a R or python user and I don't know or even deeply visited any website about but @Thalie's example looks good with a "functionality" entrance and an attractive gallery look (as Shiny's gallery).
The french website geotribu.net invited me last year to write about using ODK in a GIS context. They try to maintain a publication regularity alternating between articles and press review, relative to open-source geomatics.
This regularity (not necessarily this frequency) is important to keep users attentive to the website.
Maybe a kind of periodic review could keep users in touch with ODK community. Discourse's Digest (Activity summary) is a first available possibility. It can be set to expose particular categories or tags. It is sent people who did not visited the site for a while. It is not really beautiful or attractive but informative.
I think whatever the tool used, a regular schedule is important, the frequency must be a balance between animation effort from the Tab members working on it, writing effort from solicited users and "standby time" from readers.
Maybe the actual showcase, with some animation effort and an up to date showcase index would be a good starting point.
The showcase index, once updated, should be pinned permanently on the top of the Showcase category.
I saw this week that it is wiki mode 
so we can edit it.
And I'll take some time to.