Edit: The ARRL has restored their previous page showing other study options! You can find it here: http://www.arrl.org/instruction-exam-practice-and-review
You may or may not know that HamStudy.org is more than just a website for studying; we are a small organization (official ham club with the call sign NT3ST) which is dedicated to improving and modernizing the state of Ham Radio exams and testing. We believe strongly that Ham Radio is a hobby (or sport, if you prefer) for all walks of life and all people.
We believe that all who have interest in the air waves for non-commercial interest should be welcome: HF code guys, HF voice rag chewers, 2m service buffs, preppers, RF aircraft hobbyists, appliance users, electronics hackers, and anyone else who wants to join. Ham Radio should be about cooperation, openness, and community.
This is why we were so disappointed this morning when we discovered that the ARRL has removed links to all other online systems for studying for an Amateur Radio license other than the one they released about a year ago which seems to be designed to help sell their books.
Update Nov 29, 2015: I just discovered that the ARRL does still have this information on their website, it’s just hidden on a page that not many people know about.