The list is comprehensive but some projects seems outdated or not not active anymore or replaced by other projects outside of the GNU projects, I’m reading bout each project and will compile a list of the projects that is interesting for me here:
AVL: a library for using AVL trees and binary search, this means you don’t need to write AVL trees and balancing them yourself, just use this library.
Dia: graphing software I used to use long time ago, it’s very useful for drawing diagrams and didn’t know it’s maintained by GNU
fribidi: a library for UTF bidirectional algorithms, this is the one responsible for drawing the characters in the right direction when you’re writing arabic/hebrew and english, without it you’ll find applications that draws the arabic characters separate from each other or in reverse
GnuComm: free telephony system consists of 7 projects for routing calls and handling them, that was the most surprising project for me, this means I can build my own home made telephone system inside a company or a building without the need for a central telephone network.
Gtick: That’s a fun one, this is a metronome, it ticks :D I had to try it and I don’t know why it’s satisfying to hear.
Anubis: I’m egyptian so the name itself qualify it to be on this list :) what it does is preprocessing an email before sending it to a MTA
Gift: query images by example without annotations, so this is basically google images search on my machine?
GnuDOS: that’s an odd one, a library to help people coming from DOS and started using GNU system
GNU Jump: a clone of the famous game icy tower, I used to play this when I was a kid :), I tried it and it was very funny, the sound was made by the developer mouth and when you fall you hear him screeming :D
liauid war 6: That’s a weird game, I didn’t understand the rules but it’s like you have an army represented in liquid form and you move it against your enemy other liquid army.
Phantom.Home: a circuit to control any 120V home appliance, I don’t fully understand it but the idea is interesting
barcode: I like this one, it convert any string to barcode in ps format
Dr. Geo: That’s an interesting one, it allow you to define interactive geometric graphs, then you can manipulate this in a UI, it’s useful for kids for education.
Gnubik: rubik’s cube puzzle
Gtypist: This was useful to me when I wanted to learn touch typing, it’s free and work in a terminal.
GNU Recutils: manage human readable database files
Units: This is very useful yet I always forget about it, it converts measurements from many units.
Ocrad: OCR program, didn’t know that it exists.
Pipo: GNU BBS!
Dionysus: a library of scientific and engineering constants
GCompris: kids education software, I see they can teach kids math, words, colors, reading the clock…etc, it says for kids from 2 to 10 years old.
GnuCash: Accounting software for persoanl and small business financial accounting.
LilyPond: Music note sheet generator
GGradebook: this program is for teachers to grade their students!
GNUtrition: hutrition analysis software it uses a standard database for foot nutrient information.
PJP: personal expenses manager, runs in terminal, not like GnuCash
A notable document I found was related to GnuSocial that specify a W3C recommended protocol for social media applications called ActivityPub