Wappalyzer is great browser extension which can help identify what technologies a web site is running on the back end. Knowing what services are running behind the scenes could be your way in.
Once you have installed, it will appear in your address bar to the right. From then, it will help identify what each site is running. It won’t be able to pick up everything but it will certainly try.
Now just image if you are crawling through a site and you see CMS Made Simple is being used or some exploitable WordPress plugins are running. You would be able to search the Exploit-DB and potentially find an authentication bypass or a way to extract credentials. It’s defiantly one for your toolbox.