Facebook's networking blog is a great place to get inspired - https://code.facebook.com/posts/networking/.
Check ONF SDN skills certification program pages for disruptive view on SDN. For more traditional vendor programmability, check Ansible and NAPALM.
For public cloud networking, check AWS and Google networking certifications. Resources to prepare for exams: AWS - free course from AWS. GCP: blog post
For private cloud networking, consider MidoNet. For large-scale deployment, try OpenContrail sandbox. If you have powerful servers, try installing OpenContrail.
If you want to learn OpenFlow-related things, consider mininet.
To find more SDN-enabled producst visit ONF product listing, OCP specs and designs
Some concepts described on sdntutorials.com
OpenStack with OpenDaylight
OpenStack with OpenDaylight: A Hands-On Workshop: part 1, part 2
Network programmability
Cisco labs - Network Programmability for Network Engineers
Python / Ansible for network engineers - https://pynet.twb-tech.com/
Yang / NETCONF
Tail-f training videos and the PowerPoint decks
Short overview of OpenDaylight's support for NETCONF - https://www.youtube.com/watch?v=gQa1Z0cK9Ko
SDN-enabled practical cases:
SDN WAN lab with ODL - http://blog.alainmoretti.com/how-to-start-with-opendaylight-automation-for-wan/
Segment Routing with OpenDaylight Beryllium - http://www.packetdesign.com/blog/segment-routing-with-opendaylight-beryllium-a-packet-design-how-to/