Not completely *systems*, but a genuinely interesting and useful tool concerned, I’d say, with pattern spotting and recognition, and exploitation,
Other items:
Simon himself (slides and speaker notes): https://www.slideshare.net/swardley/an-introduction-to-wardley-maps
What do Wardley maps really map? A settler writes
https://blog.gardeviance.org/2015/02/an-introduction-to-wardley-value-chain.html
And now an interesting though not yet fully integrated pairing with Cynefin:
Systems Community of Inquiry 