I absolutely love what you are doing with Biblia.com I love that I can access my library anywhere there is computer access. On my computer I have the Libronix digital library system which has a really cool Exegetical Guide feature. Unfortunately I don't see this feature in Biblica.com yet. I would love to see it added soon!
In addition I also think you should add some free high quality bible resources like they are doing over at www.mystudybible.com They are offering free New Testament commentaries and Bible dictionaries as well as the HCSB Study Bible... all for free! I think Logos should follow this line of thinking as well.