Extended longevity of a HTC One S using Cyanogenmod

The mobile

I own a quite old - at least by today's standards of planned obsolescence for every consumer device - HTC One S (2012), that won't be receiving any more Android upgrades (last update: version 4.0.4) or support by its manufacturer directly or any distributor for that matter.
It's quite a nice, small and lightweight phone, that by now has seen the world and besides a self-administered chassis change hasn't yielded any serious problems.
The phone doesn't have much RAM or much space. Neither does it have a microSD card slot, NFC or other fancy new stuff that people seem to need.

CyanogenMod

The alternative firmware for some mobile devices CyanogenMod is available for free and offers a community driven development branch of the Android kernel, without the Google and mobile vendor bloat.
Have a look: Maybe your phone is amongst the supported devices?
Not all vendors allow flashing other firmwares though. Some prevent this completely (watch Cory Doctorow at 28C3 for an in-depth comment on this), others let you do it by voiding your warranty, yet others just let you do it, because they are awesome.
All CyanogenMod capable devices have development codenames. For the HTC One S this is "ville".
Each device offers a release channel (with stable releases) and a development channel (with nightly builds for the adventurous and daring).
An install section explains how to get CyanogenMod on your device.

F-Droid

F-Droid is an alternative app store to Google Play. It only offers free/libre software. This is pretty awesome.
Some useful apps I like, use or have used:

Guardian Project

The Guardian Project offers a repository for F-Droid with free/ libre Android applications that are being developed by a team of volunteers and are all evolving around the matter of strong encryption for communication.
One of the more notable projects was to bring Tor to Android.
The Guardian Project has more buns in the oven though. Some are directly available through F-Droid, others only through their own repository. This is a collection of the currently available projects:
  • ChatSecure - A free and open source messaging app that features OTR encryption over XMPP
  • Orbot - A free proxy app that empowers other apps to use the internet more securely
  • CameraV - The easiest way to capture and share verifiable photos and video proof on a smartphone or tablet, all the while keeping it entirely secure and private
  • ObscuraCam - A photo and video app for Android that keeps certain information private.
  • Pixelknot - An Android application that allows users to hide short text-based messages in photographs and share them across trusted channels.

Conclusion

Yay!

  • I don't need to buy a new phone each year, because my battery got eaten by malicious apps that I can't disable.
  • I can use an Android device without Google
  • I can use an Android device without vendor bloat
  • I can use an Android device as root and modify it the way I want it
  • I can choose to only install free apps