Qur’anic Study Tool
During my study of the Qur’an, I came across this website:
I have to say, I’m really rather impressed. The site allows me to compare different Qur’anic translations, which has proved very helpful in discerning the meaning of obscure verses:

It also has an ontology graph, showing the relationships between different concepts in Islam.

There’s also a considerable material here on grammar, which I’m sure I’d find useful if I actually spoke Arabic:

The only thing it doesn’t have which I’d find really helpful is integration with the hadith, since context is still my #1 issue when reading the Qur’an…

Fr. Robert Barron’s website, 

Okay, small rant alert…