Somewhat off topic, but there are rumors of a fifth Indy film eventually coming to pass.
http://www.inquisitr.com/1316017/indiana-jones-5-harrison-ford-is-on-board-despite-leg-injury/
If they ever do get around to making this film, I hope they deal with a Muslim relic. The Ark of the Covenant was a Jewish relic, the Grail a Christian one, and the Sankara Stones are Hindu, all three antiquities from great religions. It seems that Muslims in general are more easily offended, which is possibly why they haven't done so before. Nevertheless, I feel it could be truly interesting and an opportunity for insight into Islam. Indy often travels to Egypt to visit Sallah. Why couldn't he travel to the Arab world again, this time to rescue some important object in Islam? In an Indy RPG, the Black Stone goes missing. Such could really be an interesting pretext in my mind, especially if they were to make a more serious sequel.