Sticky cydia tweak is a highly customizable sticky note tweak. Have notes on your lock screen similar to how the sticky notes on a PC works, except with more features! Have a look a the video below for a better idea on how this tweak operates. It is extremely light weight.
The sticky notes are themable as well! You can theme them to your liking by editing the images, or using winterboard, in the preferences bundle. The bundle can be located here: /Library/PreferenceBundles/Sticky.bundle