There are many ways to make quiet MP3 files louder ("Normalize"), but the easiest is by far using Audacity, since you can process multiple files at once (also known as batch processing) with the Macro tool:
Save paper by printing on both sides of the paper (duplex). If your printer is able to print on both sides and is installed to support CUPS, you can define default setting such as changing paper size from Letter to A4 and duplex printing at http://localhost:631/.
QGIS is an open source program which allows you to: "edit, visualise, analyse and publish geospatial information on Windows, Mac, Linux, BSD and mobile devices. For your desktop, server, in your web browser and as developer libraries."
Setting up a Linux installation can be done in many different ways, but preserving your settings and bookmarks is nice, so you don't have to redo them after a re-installation. This set-up uses another partition (in the example, called "documents") to store your photos, documents, settings for installed programs and your mail program, and connecting to them via symlinks.
Sometimes, the font size on a web site is too small, for example at https://www.retsinformation.dk/ where the font-size is 11.2 pixel. You can override the text size locally, via the userContent.css file.
Also, highlighting links can be useful, to allow tabbing between them.