Bible Gateway Offers scripture reference and keyword search, multiple translations, including a side-by-side comparison feature
Bible Hub Offers scripture searching with "topical, Greek and Hebrew study tools, plus concordances, commentaries, dictionaries, sermons and devotionals" - lots of great research options!
Blue Letter Bible Scripture research and study tool that includes line-by-line Greek, commentary notes, multiple translations, and cross-references
Got Questions? A non-denominational site offering "over 5,200 answers to frequently asked Bible questions" based on prayerful, Biblical research
Thou Art Exalted This site offers Bible studies, curriculum, and artistic, hands-on resources for tweens - young women that are designed to "creatively equip this generation to know Christ through the study of God's Word." Highly recommend their easy-to-use app for devotionals!
Seedbed - The Daily Text A devotional including a scripture passage, prayer, and discussion questions delivered to your inbox daily. Developed by faculty and staff of Asbury Theological Seminary, the main Seedbed site has other helpful Bible study and theological training resources too.
Why Online Courses? This is a great overview of reasons for offering online Christian education opportunities and points out resources for starting them.