The National Numismatic Collection at the Smithsonian is one of the largest collections in the world. I have seen parts of it, but have never had the opportunity to see as much as I would like. It includes the original collection of the U.S. Mint as well as the Josiah K. Lilly gold collection and more - over 1.6 million objects. It is also the only place in the world where you could see two 1933 Double Eagles.
However, you may never get the chance to visit the Smithsonian and even if you do, you may not have the luxury of seeing everything you'd like to see. You can see some of it on-line, but unfortunately only a few hundred pieces are shown. It does include some of the more interesting objects like a 1933 Pismo Beach Clamshell Dollar, 1804 Dollars and interesting patterns like this 1792 pattern quarter, but the selection is disappointing.
National Numismatic Collection
It's not just the paucity of on-line items. Surely there is more to say about 1933 Double Eagles than this?
They do say:
We are working to expand and improve online access to additional objects in the near future, so stay tuned.
I certainly hope so.
National Numismatic Collection On-Line
Contests and giveaways: http://coins.aplawrence.com/2014/05/contests-and-giveaways.html