Backbone-todos-in-steps is a project mainly written in ..., it's free.
Backbone todos in incremental steps to better understand how the todo app works.
http://backbone-todos-in-steps.bigbinary.com
step2
step3
step4
step5
step6
step7
step8
step9
step10
step11
step12
step13
step14
step15
step16
step17
step18