- Oxford English Dictionary, 2nd ed. (20 volumes)
The Concise OED is nice, but it doesn't have all words I come across in it. I've been a fan of the complete and unabridged Oxford English Dictionary since childhood. My mother had the 2-volume complete but reduced print edition that had such tiny print you had to read it with a magnifying glass (which came with it in a little drawer). I've had access to the online edition through my graduate school for years. It would be awesome to have this resource in Logos format. It is/was published by Oxford on CD-ROM a while back, but I never bought it because it was expensive and I figured it would be obsolete before you knew it. But if it were in Logos format I'd be assured it would be kept from obsolescence as long as I had it. The thorougness of definitions is great, but the other wonderful thing about the complete OED is all the quotations of when a word was used in significant ways in the past. It includes a lot of Christian literature, so it would make a fascinating browse, and including it in a full library search would come up with some great quotes from certain individuals.
This would be well worth several hundred dollars in Logos format, though I'd hope they could do it for $150 or so.