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

Bibliographies with biber and biblatex
How to use biblatex with bibier and hyperref package.
Frank the Bunny

The Chicago Citation Style with biblatex
The biblatex-chicago package implements the citation style of the Chicago Manual of Style, 16th edition. In this example, the notes option causes biblatex's autocite command to put citations in footnotes. The package can also produce inline author-year citations in the Chicago style. See the package documentation for more information.
writeLaTeX

Automatic Glossaries in LaTeX
This example shows how to generate automatic glossaries with the glossaries package. For more information, there's a good guide in the LaTeX wikibook, and also in the package documentation.
writeLaTeX

A simple example showing how to create Harvard style referencing in LaTeX
The following examples show how to produce Harvard style references using biblatex.
See this post on TeX StackExchange for further discussion on the Harvard referencing style, and this post for more details on switching to biblatex if you're more familiar with e.g. natbib.
John Hammersley

Bibliographies with biber and biblatex
This example shows how to automatically generate citations and a bibliography with biblatex and biber.
Biblatex and biber work together to automatically format references and citations like the older cite or natbib and bibtex tool chain, but they offer more powerful and easier to use formatting and better support for special characters (unicode).
For a full list of biblatex styles, see the user guide in the biblatex manual.
writeLaTeX

Using Thai font in XeLaTeX without uploading fonts in Overleaf | การใช้งานภาษาไทยใน XeLaTeX โดยไม่ต้องอัปโหลดฟอนต์
Since version 0.7.0 of fonts-tlwg is published, XeLaTeX users now can specify Thai fonts from those package without having to upload them manually. This creates a better Thai XeLaTeX experience especially on online platforms such as Overleaf.ตั้งแต่ fonts-tlwg ปล่อยเวอร์ชัน 0.7.0 ออกมา ทำให้ผู้ใช้งาน XeLaTeX สามารใช้งานฟอนต์ภาษาไทยโดยไม่จำเป็นต้องอัปโหลดฟอนต์เองอีก ทำให้การใช้งานภาษาไทยใน XeLaTeX ทำได้ง่าย โดยเฉพาะสำหรับโปรแกรมออนไลน์อย่าง Overleaf
Abhabongse Janthong

Espectro de Banda Base OFDM Multiportadora Logarítmica
Este listado LaTeX es una versión logarítmica del proyecto "Espectro de Banda Base OFDM Multiportadora" que muestra las notorias diferencias en el trazado de las curvas del espectro OFDM correspondiente a 4, 16 y 64 subportadoras, cuando se aplica una escala lineal logarítmica en base 10. Esta figura se basa en la mostrada en la página 643 del texto "Digital Modulation Techniques, Second Edition", de Fuqin Xiong, de la editorial Artech House, Inc.
Ramón Jaramillo

Flashcards in korean
Example of flashcards of vocabulary in Korean.
Abril

Aula sobre Gráficos no Latex
Aula sobre Gráficos no LaTeX ministrada pelo professor Egmon Pereira a alunos do primeiro período de Eng. da Computação do Cefet-MG Unidade de Timóteo.
Egmon Pereira