I don't really follow any dogmatic Agile[0] practices such as Scrum or Kanban, but for the last two or so years I've exclusively used Trello[1]. It is lightweight enough that it isn't in my way. I more or less treat it as an online persisted post-it note wall.

0 - http://rubiquity.com/2014/03/12/agile-is-dead-angry-develope...

1 - https://trello.com/