The National Association of Scholars just published a list of brain-challenging books that they recommend for college reading programs, but which should be of interest to any passionate adult-level reader. These books were selected for presenting important, well-argued ideas with a level of complexity that stretches the mind -- basically they function as upgraded "beach reading" for the scholarly set.
Many of these titles are freely downloadable in ePub format and can be synced to iBooks for your portable reading pleasure. Here's a quick run-down of some of the recommended books, along with quick links to iBooks-compatible downloads.
Flatland by Edwin Abbot (Illustrated version)
