Bible Gateway, Bible Resources and Bible Study Tools all provide free online Bible verse look-up tools. Each of these sites offer many different translations of the Bible to search from.
Bible Resources provides a search tool for 18 translations of the Bible. The tool is capable of searching by word, phrase, verse and chapter number. Bible Gateway's search tool functions across many translations and versions of the Bible and can look up verses by keyword or topic. Bible Gateway also offers a mobile app, available on iTunes and Google Play, that contains many of the same functions as the full website.