Sometimes to not forget to do something it's enough to write it down in a prominent place. On Android you can add any message in the notification bar.
This is autotranslated version of this post.
Pinnit allows you to add tasks to the notification bar.
To add a message to yourself, or task, run the application and click Create. In the next window, you can add a short name and a little more detailed description.
Then click Save and pin and the task will appear in the list and in the notification bar.
When you click on Unpin the notification or the icon buttons in the list, the task is removed from the bar, but remains in the list.