The Fledgling Languages list has almost 100 programming languages that are up-and-coming but not widely popular. I looked at them all and here are a few of my favorites:
...This language looks so much like English! http://www.availlang.org/
...This language claims to have the speed of C++, the expressiveness of Python, and tons of additional safety with first-level contracts http://cobra-language.com/
...Code that looks exactly like Ruby, but is statically type-checked and compiled into efficient native code http://crystal-lang.org/
...What it would look like if Haskell and Clojure had a baby https://github.com/LuxLang/lux
...And if they had a second child as well https://github.com/seliopou/typo
...And another language with pretty sweet types http://ceylon-lang.org/
...A pretty cool language that has many of the features of C while being written like Python https://github.com/riolet/rix