The NY Times has an article (Tunisia Battles Over Pulpits, and Revolt’s Legacy) about the role of Salafists in Tunisia. They don't recognize democracy and violently try to impose their will - taking over mosques, destroying selling points of alcohol, etc.
According to the article the Tunisian government is slowly taking back control of the mosques. Some 800 Salafists are already in prison. But it looks like the Salafists are getting stronger in other areas.
These Salafists are a good illustration of the old principle that you can't have other armed groups outside the control of the state. The violence monopoly of the government is one of the most essential foundations of democracy. When you have armed groups around they form a kind of alternative government and some people will look at them for that. That explains why a considerable number of people will feel attracted by such armed groups.
This explains also why I am so vehemently against those "democratic" uprisings in Libya and Syria. They undermine the violence monopoly of the government and in that way make democracy less viable.