I have tonnes. Sometimes they're applications, sometimes they're libraries. Recently I've been interested in random experiments to push my exposure to ideas in strange ways. Most recently I wrote a redis module for encryption (https://github.com/chayim/redicrypt). My current project asyncronously fetches me status from various services (GitHub, Jira, Travis) so that I can track all sorts of things.

Personal use is the biggest driver of my ongoing learning.