I found a very nice SSL Threat model on this web page and would like to find more on different topics.
How would I go about locating more images like these? Is there an organisation or website I could go to?
SANS.org have a few really good resources. Including:
Also for web application try https://www.owasp.org/index.php/Threat_Risk_Modeling.
If you like to get into the basics of Threat Models, then Threat Modelling from Microsoft Press is a nice book. Don't be put off by the introduction-page, it is an overall fine beginner read.
MyAppSecurity's ThreatModeler uses a software centric approach to Threat Modeling. It includes a feature to view an Attack Graph / Threat Pattern for individual software components.