Also devtodo [0] (written in Go) and todo [1] written in Python.

[0] https://github.com/alecthomas/devtodo2

[1] https://github.com/foobuzz/todo

And http://todotxt.com/ if you want to sync between the CLI and your phone.

And quite big community.

And Jrnl which is one I use on a daily basis. http://jrnl.sh