I am sharing my favorites with you. This is by no means an exclusive list. Start here. Build your own set. I started to share what I titled them and a description, then decided, “NAH”. Do it yourself. It will be better suited to you that way.
Ham Exams Online
https://hamstudy.org/
My favorite online exam preparation tool is HamStudy.org I highly recommend using their Study Mode and clicking on their tab to understand the WHY of each correct answer. Use their Test Mode rarely to get a snapshot of your progress towards passing the upcoming exam.
http://arrlexamreview.appspot.com/
https://www.mometrix.com/academy/?s=amateur+radio
Ham license information
http://www.arrl.org/advanced-call-sign-search
http://hamdata.com/fccinfo.html
http://hamuniverse.com/hamcallsigns.html
radio hardware
https://www.dxengineering.com/
https://www.smileyantenna.com/category-s/1814.htm
http://kv5r.com/ham-radio/2-meter-sleeve-dipole/
https://nsw.wicen.org.au/technical/projects/coaxial-folded-dipole-antenna
Operations
http://www.bandconditions.com/
https://www.eham.net/
http://www.hamqsl.com/solar.html
http://hflink.com/propagation/
https://www.scc-ares-races.org/generalinfo/phoneticalphabet.html
http://qrznow.com/real-time-band-conditions/
Training
https://brushbeater.wordpress.com/
https://www.americanpartisan.org/2018/11/writing-a-tactical-soi/
https://brushbeater.wordpress.com/training-courses/
Math and Science – YouTube classroom lessons
(scroll down for Engineering Circuits)
Antenna Basics