The SI system

• A comprehensive (SI) units package for LaTeX, by Joseph Wright. I cannot recommend this package enough for all scientific or technical documents. CTAN.

Code examples

• Semiconductor pn-junction diagram in TikZ, by Erwann Fourmond (2016)
• Schematic TEM in TikZ, by Eric Jensen (2012)
• Oxidation of iron surface under a blob of water in TikZ, by Jason Waskiewicz (2010)
• Designing a business card in LaTeX, by Olivier Peters. Github repo.

Templates

• LaTeX packages for CVs, resumés
• PhD thesis template for Cambridge university Engineering dept. Supports LaTeX, XeLaTeX and LuaLaTeX.

Integration with R

The ability to integrate any kind of R output into our LaTeX document is very useful, and the technology has reached a high degree of sophistication with knitr and tikzDevice (on the R side) and TikZ/PGF (on the LaTeX side).

• TikZDevice, an R package for producing graphics output as PGF/TikZ code for use in TeX documents. In other words, we start in R, generate an image, and export it to a TikZ picture. tikzDevice was developed around 2009 (here's an early demo) in concert with pgfSweave (this was before knitr entered the scene).
• dvir, offers the inverse approach to tikzDevice: we start in R, generate a TikZ picture, convert that to DVI, then import (and integrate) the result back into R. dvir is less popular than tikzDevice, and is currently not listed on CRAN (in fact, it clashes with an existing completely unrelated package named dvir), but appears to have solid technical underpinnings, with LuaTeX support and LaTeX math support.

Integration with Inkscape

• SVG2TikZ, formally known as Inkscape2TikZ, is an Inkscape extension for exporting SVG paths as TikZ/PGF code.

Integration with Microsoft PowerPoint

• IguanaTeX is a PowerPoint add-in which allows you to insert LaTeX equations into your PowerPoint presentation.

Integration with git

• gitinfo2-latexmk, small tool that integrates latexmk and gitinfo2.

Integration with Zotero

• Better BibTeX, a Zotero extension that makes Zotero effective for LaTeX users.

Integration with the web

• TeX commands available in MathJax, a comprehensive list of all commands available in MathJax v2.7.1, by Carol Burns and edited by MathJax creator Davide Cervone. MathJax v2.7 is still widely used, but has technically been superseded by v3. MathJax.
• KaTeX, developed by Khan Academy. Known to be faster than MathJax, but supporting a smaller subset of TeX/LaTeX functions. Differences between the projects appear to be shrinking, though.

Cloud-based LaTeX

• TeXLive.net
• Overleaf

Other packages

• Beamer, package for producing presentations and slides. Github.
• FiXme, collaborative annotation tool for LaTeX. Github.

Tips and tricks

• On managing large documents.