Back in January 2016, Myriad had an ATL market cap of $25,000 and each coin was worth 6 sats. Now its market cap is $750,000 and each coin is worth 40 sats. Vertcoin is another example. In mid-2015, it had a market cap of $100,000 and each coin was worth 2,500 sats. Now its market cap is $3.5 million and each coin is worth 9,000 sats.

Probably the most famous example these days is PIVX.

Coins such as these tend to escape the attention of most people. When a coin goes from a $20 million market cap to a $200 million one, it's a big deal. But when a coin goes from a $100,000 market cap to a $1 million one, very few people will take notice. And that's despite the fact that the return on investment is identical for both.

More importantly, it's far easier to bring up a coin's market cap from $100,000 to $1 million than it is to bring up a coin's market cap from $100 million to $1 billion since the former requires a far smaller injection of money. Lots of coins with market caps in the tens or hundreds of thousands of dollars have increased in value by 10 or 20 times that of BTC. Very few coins with market caps already in the hundreds of millions of dollars have done the same (Ethereum might be the only one so far).

So, anyway. That's probably enough rambling from me. What are some of the more promising very low market cap altcoins out there?

EDIT: Just to clarify, I'm not saying that Myriad, Vertcoin, and PIVX are currently promising altcoins with low market caps. But only that they were so in the past. I have no idea what these coins will do in the future.