Narender Singh form ForcePanda wrote a two blog series about using map collections in flows. The second blog makes good use of the new generic sObject support in flows coming in the Spring ’20 release
Part 1: https://forcepanda.wordpress.com/2019/12/17/how-to-create-a-map-collection-in-flows-part-1/
Part 2: https://forcepanda.wordpress.com/2019/12/18/how-to-create-a-map-collection-in-flows-part-2flow-map-methods-spring20delight/
GORAV SETH shared a quick tip on his blog about a way to create a unique collection in flow
https://goravseth.com/creating-a-unique-collection-in-flow
A common need in Flows is to be able to redirect the user to a new record that may have been created in the Flow. This new Lightning Flow Action can be used to redirect the user to the specified record in either View Mode or Edit Mode.
The admins at https://www.xbaf.com wrote a blog on how you can create a list button that launches a flow and pass the selected record ids to be processed by the flow using an undocumented flow variable
Narender Singh form https://forcepanda.wordpress.com posted a series of blogs on how to add validation to custom flow screen components:
Narender Singh created a flow screen component for a dependent picklist tha supports picklist value selection based on the record type.
https://forcepanda.wordpress.com/2019/06/11/flow-screen-component-dependent-picklists-with-recordtype-and-multiselect-picklist-support/
Douglas Ayers and Michelle Hansen developed an Apex trigger that could know when a file was being shared to a record and then call an autolaunched flow where the business logic could be implemented declaratively.
Ever wanted to inject Einstein Next Best Action into your Flows? Check out this post by Marc Baizman.