C

• Darknet - Darknet is an open source neural network framework written in C and CUDA. It is fast, easy to install, and supports CPU and GPU computation.
• Recommender - A C library for product recommendations/suggestions using collaborative filtering (CF).
• neonrvm - neonrvm is an open source machine learning library based on RVM technique. It's written in C programming language and comes with Python programming language bindings.

Go

Speech Recognition

• snowball - Snowball Stemmer for Go.

Lua

Speech Recognition

• imgraph - An image/graph library for Torch. This package provides routines to construct graphs on images, segment them, build trees out of them, and convert them back to images.
• OverFeat - A state-of-the-art generic dense feature extractor.

Python

General-Purpose Machine Learning

• nut - Natural language Understanding Toolkit.
• Bolt - Bolt Online Learning Toolbox.
• somoclu - organizing maps: accelerate training on multicore CPUs, GPUs, and clusters, has python API.
• Retro - Retro Games in Gym

Ruby

General-Purpose Machine Learning

• Stemmer - Expose libstemmer_c to Ruby.