This is amazing, easily add todo notes to your Latex file while you are still working on it. They will show up as a bubble on the right side of the PDF file, with a line pointing to the actual position in the text.
Usage is as simple as that, include the package:
\usepackage{todonotes}
Add todos:
\todo{Your task}
You can download the package from here. In order to generate the stylefile, open the *.ins file in your tex-editor and typeset it, creating the *.sty file.
ps.: You might have to typeset your document twice for the line to show the actual position of the task.
pps.: If you don’t particularly like the color, open the sty-file with your tex-editor and change the color to anything you like. The commands to change can be found in the beginning of the stylefile (backgroundcolor & linecolor).
Example:
\documentclass[12pt]{article}
\usepackage{todonotes}
\usepackage{blindtext}
\begin{document}
\section{Introduction}
\todo{Replace dummy text}\blindtext
\end{document}