On a user-friendlyness note, it could be fun to use ChipIn (http://www.chipin.com/ ) instead of the standard PayPal Donate service. It is always fun to track progress. You could enable a Past Donations subsite to www.mises.org/donate.aspx where users can browse through what have been donated in past time and what it have enabled LvMI to do.
And a last idea or now.
LvMI is full of very valueable information. But to most people and even me, it can sometimes be a daunting exprerience to dig through the archives. My suggestion is if it would be possible to make information access more visually interactive. My concrete suggestions are to implement CmapTools cmapskm.ihmc.us/.../SBReadResourceServlet or http://www.deepamehta.de/ which both are free, or BrainEKP http://www.thebrain.com/#-48 which is very expensive.
gcopenhaver previously suggested moving LvMI to Drupal. I am not a developer myself, but from what I've heard, Drupal is a very good all around CMS (soon to beat Django), but I think ultimately Drupal wouldn't be able to build something better than the current mises.org. But I do think that Plone might be an option to transform LvMI into something bigger than what it is now. But Plone requires knowledge of Python (and a little Zope perhaps). (Github might be useful as a revisioning system for the development process.)
I believe the site for the LongNow Foundation, http://www.longnow.org/, is built on Plone. At least I know their Rosetta Project *is* built on Plone, http://www.rosettaproject.org/ .
If of any interest, I can help translate into Danish...