In my experience these coins tend to provide the best potential for massive returns. The ones I've found so far are:
QBIC - 700k market cap -
https://qbic.ioMasternodes, P2P instant/private payments, and a really really low market cap. Not listed on any decent exchanges yet, but can get on SouthXchange. Even the slightest positive news could move this project to 5-10x it's current market cap. Roadmap looks promising.
Obsidian (ODN) - 2 million dollar market cap -
https://obsidianplatform.com/Project is about to fork into two coins. The premise is good (private messenger with payments), it's PoS and should definitely be valued higher. There are some small issues with the coin and team going on right now and that's the reason for the low cap, but if you believe in what they're doing it could be a great time to get in. Also available on Cryptopia.
If you have any other suggestions for extremely low cap coins with high potential post them here and I'll add them to the list!