A couple of weeks ago Trello announced a big revamp to their notification system, along with a new and centralized home page where you not only view the said notifications but also manage all cards that require your attention. That includes card you’re following, mentioned on, and with due dates coming up.
This is particularly useful if you have multiple boards to handle different aspects of your life, and of course different clients. This is update is live for all desktop users, I’ve been using it and it’s great. I don’t think it’s available in mobile apps just yet though.
Fun fact mentioned in their blog post, 2 hundred million cards have been created on Trello so far, if these were stick notes they’d require a wall 160.934 kilometres long!