Coin and currency collectors hold history in their hands! Common grade circulated coins are inexpensive and fun to collect. Carefully chosen rare coins qualify as investments.

PCGS 3000 Index
An index of 3000 rare investment-grade coins whose prices are tracked and reported by coin experts at Professional Coin Grading Service (PCGS).

PCGS Price Guide
Listing of American coins in various grades with current prices as determined by PCGS experts (not perfectly accurate, but at least it's a fairly reliable guide).

PCGS Photograde Online
High-quality photos of most U.S. coins, in various grades, as judged by PCGS, to aid the amateur in grading their coins accurately and gain confidence in their own grading skills.

The best ex-U.S. coin guide. Photos and detailed descriptions of world coins from all historical periods. A "comprehensive universal numismatic catalog."

World Coin Price Guide (NGC)
Valuation guide and database of world coins minted since 1600. Maintained by Numismatic Guaranty Company (NGC), the penultimate coin grading service (after PCGS).

Coin identification app enabling collectors to identify a coin just by snapping a photo, returning a list of similar coins. Fast and surprisingly accurate. A must have.

Coin Supply Express
The online outlet I use to get all necessary coin collecting supplies. CSE was the one I settled on after doing a lot of research. Good prices, decent service.

eBay: Coins and Paper Money
One of the best, most popular places to buy and sell coins is on eBay. All kinds of coins from all kinds of sellers at all kinds of prices. Pay careful attention to seller ratings.
Excellent bullion coin price comparison site. Before buying bullion of any kind, you'll want to check prices on this site to be sure you're getting a good deal.

SD Bullion
One of two reputable online bullion dealers I recommend. Very good prices. Excellent reputation. There are shady, difficult dealers out there. SD is not one of them.

Hero Bullion
Another good online bullion dealer. Compare Hero's prices to SD Bullion, then take a trip to FindBullionPrices before buying bullion coins.