I have to say that Egypt seems like one of the main sources for radical Islamic thought across the world. I know people always talk about Saudi Arabia but think of the people that have come out of Egypt - Qutb, Zawahiri, Abdullah Ahmed Abdullah... even the birthplace of the Muslim Brotherhood, offshoots of which can be found throughout the Arab world, was in Egypt. it's quite striking when you see just how many Al-Qaeda members came originally from Egypt. It's probably because Egypt is one of the most populous Arab countries, but the proportions of the population that adhere to strong, Conservative Islamic teachings are surprisingly large. I think of all the Arab countries that could stage a successful Islamist rebellion, or at least start another civil war over it, Egypt would be that country.
I'd say Egypt was the cradle of modern radical Islamism. In particular the eerily familiar 1952-4 situation.
In 1952 there was a popular military uprising against the monarchy. A Revolutionary Command Council was formed that suspended the constitution and announced a three-year transitional period during. The Muslim Brotherhood supported them in the coup, but then opposed the secular constitution proposed. During 1953 there were open clashes between supporters of the revolutionary council and supporters of the Brotherhood. This lead to the Brotherhood being outlawed in Egypt from 1954 up until 2011, although those imprisoned were released in the 70's after denouncing violence. Before that point detention, torture and even execution were the norm.
It was this outlaw status, combined with what they felt was betrayal by the revolution they had supported, that pushed them towards a more extreme and radical outlook. The inspiration for many Islamist groups (including Al Qaeda) came from the writings of these radicalised Brotherhood leaders.
The modern Brotherhood are pretty well separated from those leaders (Bin Ladin himself accused them of betraying
Qutb's ideals. That said it was always a split between wanting to engage with them and try to build a nation where they were satisfied without pulling too far in an Islamist direction or marginalising them and risking a repeat of the 50's radicalisation.