todonotes – Marking things to do in a LATEX document
From the webpage:
The package lets the user mark things to do later, in a simple and visually appealing way. The package takes several options to enable customization/finetuning of the visual appearance.
The feature of this package that grabbed my attention was the ability to easily create a list of todos “…like a table of content or a list of figures.”
In any document longer than a couple of pages, that is going to be very handy.