1. The Choice: A Fable of Free Trade and Protection by Russell Roberts (a non-technical discussion of trade: comparative advantage...) Every Economics major should read this book at some point
2. The Armchair Economist: Economics & Everyday Life by Steven E. Landsburg (a non-technical discussion of many economic topics and puzzles) Although a slightly harder read than The Choice this is the best non-technical book ever written on economics
3. The Machinery of Freedom: Guide to a Radical Capitalism by David D. Friedman (a non-technical discussion of many economic topics from the view of a anarcho-capitalist [an extreme libertarian])
4. Fair Play by Steven E. Landsburg
5. Economic Sophisms by Frederic Bastiat (although written a long time ago it is still brilliant and relevant today/ read "A Petition" first)
6. Of course you should read Freekanomics since everyone will want to talk to you about when they hear - you are an econ major.
Essays Online
1. "I, Pencil" by Leonard E. Read
Novels
1. Atlas Shrugged by Ayn Rand
2. The Moon is a Harsh Mistress by Robert Heinlein
(This is a work in progress; if you read all of these books and want some more recommendations let me know)