The changes package, distributed with TeX Live, allows the user to manually markup changes of text, such as additions, deletions, or replacements. Changed text is shown in a different colour; deleted text is crossed out. The package allows definition of additional authors and their associated colour. It also allows you to define a markup for authors or annotations. (Here's another customised example using avatars for the author annotations.)
A simple example demonstrating how to use some wiki markup syntax in LaTeX, using wiki.sty from the nicetext bundle. Be careful — not everything works, and some commands may break! See http://mirrors.ctan.org/macros/latex/contrib/nicetext/doc/wikicheat.pdf for a cheat sheet. If you're looking for markdown, check out this example!
Use the psfrag package to replace strings in EPS images, so that they are typeset with the same body font as your LaTeX document. Note that your project needs to be compiled with the LaTeX dvipdf engine. To configure this, after creating a new project, click on the Overleaf menu icon above the file list panel, and make sure the "Compiler" setting is set to "LaTeX". (The sample image is taken from the psfrag package.)
This example demonstrates how to write polyphonic or instrumental music on Overleaf, using M-Tx (.mtx) syntax.
This was made possible with a custom latexmkrc file. The music piece examples here were taken from the M-Tx documentation.
This is an example letter to illustrate the use of the brownletter.cls LaTeX class file.
Copyright 2003, (firstname.lastname@example.org)
For more Brown University LaTeX resources, please see: http://cs.brown.edu/about/system/managed/latex/