Examples of powerful LaTeX packages and techniques in use — a great way to learn LaTeX by example. Search or browse below.

Culmus Fonts for Hebrew in LaTeX
This example shows how to use Culmus fonts to write Hebrew in LaTeX. The Culmus Project provides a collection of Hebrew fonts for GNU/Linux and LaTeX communities.
Overleaf (formerly writeLaTeX) provides Culmus Fonts 0.7-r1 (as of 26 Jan 2014), in addition to the standard LaTeX fonts for Hebrew. (If you remove \usepackage{culmus}, you can see the standard fonts instead.) Also note that your Hebrew text must be UTF-8 encoded, and that Overleaf also supports entry of right-to-left (bidirectional) text in your LaTeX source.
Overleaf (writeLaTeX)

graphql-higlight
Highlight your GraphQL code right in your LaTeX code. (See also this help article and this minted example.
NyanKiyoshi

Sample Rtex document
Very basic example of including R code in a LaTeX document.
Jeremy Foote

UQAC Exemple de base 2019
L'exemple de fichier pour l'atelier Latex 2019 à l'UQAC.
Émile Bélanger

Code-Presentations Example (different ways, shown in Beamer Metropolis)
This is an example illustating how to typeset code in LaTeX, especially in beamer presentations. It uses the metropolis theme.
It is a presentation with one slide per "technique" which include some explanatory comments.
Examples shown are minted, lstlisting, verbatim, tcolorbox and knitR. The main document has the ending ".Rtex" which is required if you want it to be able to run knitR. Otherwise, you can just use normal ".tex".
It is accompanied by a blog post with more information here.
In this blog post, some complications which can arise when using code listings in beamer are discussed (package clashes, etc.), so this might be informative if you want to learn more.
Sarah Lang

Math cheat sheet example
This example was created for ShareLaTeX by Karol Kozioł and subsequently moved to Overleaf in October 2019.
Uploaded from ShareLaTeX

Headers and Footers Tutorial
This is an example document to show the use of headers and footers. "Special features" are a fancy header, initially made for a CV template, and a "final footer" which will only appear on the very last page.
The tutorial to go with it is here.
Sarah Lang