If you're really into food, the new book "Salted" by Mark Bitterman (not Mark Bittman) is a must read. Here's my story in today's food section.
Recently, when my girlfriend and I traveled to New York, we stopped by The Meadow, Bitterman's shop in the West Village. The photo above is the wall of salt. Pretty amazing selection. The salt is also available online here.
Locally, the best places I have found for buying salt are the Sacramento Natural Foods Co-op, Corti Brothers, and Taylor's Market.