As much as I love my silver coin collection, I think that paper currency has a lot more to offer when it comes to the ratio of number printed to collector cost. For instance, there are some notes with under 20,000 printed that can be had for MUCH less than a coin of the same mintage. A popular coin with this low of a mintage would be highly collectible and very pricey. Granted, I know we are talking apples and oranges. However, I think paper money has a lot to offer with (assumingly) a lot fewer collectors. With that being said, I look at the entire hobby of currency collecting as one big sleeper. Us younger collectors look at money primarily as PAPER, not coins. IMO, I can see paper money collecting really taking off in the coming years as the younger collector base expands. I'd be interested to know what everyone thinks of the future state of currency collecting, as well as particular notes that you may believe are 'sleepers.'