Latin and Hebrew
Hebrew and Septuagint
Latin and Gaelic
Slavic and Latin
Because the color blue is the color of the sky
Because the color blue is relaxing to our eyes
Because of the Sowing Circle's blue logo
Because of the blue color of the hyperlinks
New American Bible
The Living Bible
To contrast with the term "red letter Bible"
The term Blue Letter Bible sounded common and familiar
The founders thought the complex name will bring plenty of supporters
The blue is the color of the sky/heaven
CD and Internet
Here's an interesting quiz for you.