I thought I'd mention Surah Al Kahf 18 too.
Some hadith regarding Surah Al Kahf:
Narrated Al-Bara': A man was reciting Surat Al-kahf and his horse was tied with two ropes beside him. A cloud came down and spread over that man, and it kept on coming closer and closer to him till his horse started jumping (as if afraid of something). When it was morning, the man came to the Prophet, and told him of that experience. The Prophet said, "That was As-Sakina (tranquility) which descended because of (the recitation of) the Qur'an." (Book #61, Hadith #531)
Abu Darda' reported Allah's Apostle (may peace be upon him) as saying: If anyone learns by heart the first ten verses of the Surah al-kahf, he will be protected from the Dajjal. (Book #004, Hadith #1766)