TeX and friends play a very important role on things I do. Let me see if I can talk about a couple of them.
Religious
I'm the coordinator of a small choir in a parish. I decided to come up with a personal songbook to help me on keeping track of songs we use during masses or processions.
The songbook is typeset in LaTeX with help of several packages, most notably songs
, imakeidx
, expl3
and xpatch
. I have a personal database (populated by me) with 1500+ songs and a program that generates the songbook source according to a certain template. I have a couple of scripts written in Bash, Ruby and Python, the database is provided by HSQLDB (I have an SQLite version of it as well) and I use Cheetah or Velocity as templating engines.
The following images cover one of my templates. The first image show the main index of the book, sorting songs based on their titles alphabetically. We can also see TikZ doing a cameo in the letter titles. :)

The following image presents the song itself. Catholic liturgy teaches us that music is an important part of the mass. So I had to have every rite or gesture mapped to the correct song, e.g, entrance song, Kyrie, Gloria, Alleluia, Presentation of the Gifts, and so forth. I also had to map songs according to their categories and also taking the time of the liturgical year into consideration, e.g, Advent, Christmas, Ordinary Time, Lent and Easter. So I had to cross map all categories along the year. Besides, I also had to take into consideration the calendar of saints, feasts and the sacraments.
Every song is self-contained: number, title, list of authors, categories (represented by circles) and the liturgical time (represented by squares). For this version, I decided to go with a Sans version, but it's actually just a matter of taste. :)

Since I have several categories, I needed a wayto easily search songs according to their moments during the mass. That's where an index shines. For every category, I have a proper index. Note that, in the template, every time the category is typeset, the song title is already indexed.
The liturgical time plays an important role too! So take a look at every entry in the index: there are five bullets. They represent Advent, Christmas, Ordinary Time, Lent and Easter, in order! So it's a quick way for me to see if the song is appropriate to the current time and moment of mass: if we have a filled bullet, it means the song is appropriate to the corresponding liturgical time. :)

As mentioned before, thanks to templating engines, I can easily change the generated source. The next image shows another layout of the same songbook, now with TikZ all over the place. :)

Speaking of TikZ, thanks to vector editing programs like Inkscape, I can have a lot of "macros" in TikZ that draw religious elements in my songbooks and songsheets, like Christ himself in the following image. :)

Since I have a huge database of songs, I can generate songsheets for my parish. Here's one. Songs are semi-automatically selected in the database (I have a very nice algorithm), then I can analyze the result.
It's worth mentioning that there are lots of things underneath this "simple" task. For example:
Fonts have to be easily readable by people of all ages, including the elder. The less effort to read, the easier to follow and sing along.
Songs are treated as atomic blocks, so they won't be spread amongst several columns or pages (so people don't need to keep flipping pages in order to follow a song).
If a split is unavoidable, repeat important blocks, so there's one flow (for example, repeat choruses in the following column or page so you don't need to go back). As an counterexample, the following image does not cover this aspect, since it was a prior version of my algorithm. :P
It's an interaction between TeX and my underlying software infrastructure. :)
TeX typesets it, tells the box info (height, width) to my subroutines and the algorithm takes control on what to do. :)

Ergonomy matters. :)
Simple, very simple concepts (yet not so trivial to implement, I tell you) that make a huge difference. People sometimes come to me and say, "I love how you managed Word to achieve such nice layout!". Oh if they knew. :)
The next image refers to a wedding sheet I did to a friend. We can see the Gospel according to Mark. The colour is green because of the liturgical time (ordinary time). I also have a mass sheet template in case we need to add the lectures, psalm, gospel and the eucharistic prayer.

Speaking of eucharistic prayers, I had an old template for an order of mass. I actually need to rewrite a lot of stuff, but I guess you can get the idea from it (I don't like the icons too much). :)

I also have another (tiny) database of songs in which I have additional musical information (I usually know how to play most of the songs by heart, so I only populate this database according to the demand of other people). Here's one of my chorded songbooks:

Since I am lazy, I used the very same database to generate a song sheet for my parish, so people could follow the lyrics and sing along, as we see in the following image. It is just a very simple text processing and everything is ready. :)

During the holy week, we have a schedule of things that happen in the parish, from processions to masses. So I decided to give it a try and write this schedule in TeX and friends. I think the little clocks add a nice touch, don't you think? :)

One of my lovely psalmists is learning how to read song scores. Meanwhile, we use this trick to help her know where her voice needs to go up or down. :)
Very simple yet it works like a charm. Yay!

And I also have a transcript of J. S. Bach's St. John Passion in TeX and friends. We can see the original in German on the left, and the English translation on the right.

I think I have a couple more things, but I couldn't find them in my backup, so that's what I have to offer on the religious section. :)
General
I found a couple of jewels worth sharing on general stuff. At least it's a good way of seeing TeX and friends outside of the academic bubble. :)
This is a lovely happy birthday card we did for David Carlisle. Of course, David loved it. Nicola was also in charge of the cake.

I also found a TikZ version of Pikachu. Just don't ask me why I had TikZ code that generates this yellow rat. Sean liked it though. :)
It might be useful for someone's thesis, I believe.

I play Pokémon Y in my Nintendo 3DS, but I know nothing about types and stuff, so I had to come up with a table that helps me understand what the heck I was doing. Here it is.

For Valentine's day, I had a song by John Denver written with the magic of TeX. Too bad it didn't work. :)

TeX and friends also help my mom. Every time she needs a recipe, I go to the computer and typeset it for her. Then I have the perfect excuse to eat the recipe afterwards. :)

I once tried to write a letter to Santa, but that didn't work. I got a rock. Stupid rock.

And also we need to keep the football momentum in the chatroom, so we have our favourite Italian team!

Of course, we also have some internet memes:



We also do book covers in TeX:

I once had to typeset a couple of dominoes, so I wrote some TikZ code that does the trick for me nicely. I can have any combination I want! :)

And at last but not least, a timeless StackOverflow classic:

Moral of the story
There are lots of ways of using TeX and friends. Like clay in the hand of the potter, we shape TeX to do whatever our hearts desire. So we can use it to help others, in a way or another. :)
Mere macro expansions. Simple yet insanely powerful concept. :)