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

A longtable example
An example using the longtable environment to create tables that span multiple pages.
Overleaf

unit-Circle
My spin on the unit circle.
Michael McCabe

Statistics Formula Sheet
Formula sheet for a statistics course
Elizabeth McDonald

Flag of China
Flag of the People's Republic of China, according to official government specifications
Senan Sekhon

Flag of the United Kingdom
Flag of the United Kingdom of Great Britain and Northern Ireland, according to official government specifications
Senan Sekhon

NTU Formosan Glossing
This is a template for language glossing
Li-xing Yang

NSF biosketch
NSF-formatted biosketch, according to 2020 proposal preparation guide: https://www.nsf.gov/pubs/policydocs/pappg20_1/index.jsp
Jennifer Hoffman

Example Venn Diagram with isolated areas filled
This example helps to show how the isolated areas of a Venn diagram can be filled / coloured.
It was created as part of this answer on TeX StackExchange.
Other options for creating Venn diagrams with multiple areas shaded can be found in the Overleaf gallery via the Venn Diagrams tag.
John Hammersley

Venn Diagrams in LaTeX
Venn Diagrams in LaTeX