Search for specific words in the entire Quran.
These are excellent study tools. For example if you wish to find all verses in The Quran that mention marriage (or any other word), just type in your chosen word and it will search the entire Quran for you, and give you the results!
www.globalquran.com Search in up to 30 different languages!
yaqb.org (search transliteration, 13 English, 2 French translations)
www.islamicity.com/QuranSearch
www.altafsir.com/Quran_Search.asp
(Arabic words) or HERE
www.searchtruth.com (search 4 English, Arabic, French, Spanish, German, Indonesian translation) download to mobile too
www.quranix.net (word search multiple translations, nice interface)
www.submission.org/quran/WinQT2.html (search Farsi, Indonesian, Swedish translations)