Dropbox link to a lot of Apps -thanks to /u/meefmaster: https://www.dropbox.com/s/3haz1ww8hkjiwdc/big%20ios%20url%20scheme%20list%201.txt?dl=0
Here's a page from Apple's Documentation https://developer.apple.com/library/safari/featuredarticles/iPhoneURLScheme_Reference/iPhoneURLScheme_Reference.pdf
Older Reddit Post: https://www.reddit.com/r/workflow/comments/2tlx29/get_url_scheme_of_any_app
Searchable Online Database http://handleopenurl.com
Wiki with several Apps http://wiki.akosma.com/IPhone_URL_Schemes
Wiki with iOS Specific URL's http://iphonedevwiki.net/index.php/NSURL
Netflix URL Scheme http://healdb.com/netflix.html
X-Callback-URL Apps - thanks to /u/staatzstreich http://x-callback-url.com/apps/
Drafts URL Apps Some may work outside of Drafts http://drafts4-actions.agiletortoise.com/
System Preferences Posts https://www.reddit.com/r/workflow/comments/3mux7h/ios_url_schemes/cvk0ift
And https://www.reddit.com/r/workflow/comments/3mux7h/ios_url_schemes/cvirp7v