I still use an upgraded Newton Messagepad 2000 mainly for notes and journal entries. 99% of the time I remember things better with a kinesthetic act, so it's filled with a bunch of notes and other scribbles just because I needed some kind of movement (in this case a stylus on screen) to retain it in my head.<p>Alas, with how clunky it's been trying to sync with the rest of my digital life, it's currently in Dual-Carry status with a Note 8, with eventual retirement as a conversation starter on my bookshelf.
I have a 1999 iBook clamshell that my daughter now uses for school. It has been upgraded with more RAM and I replaced the slow HDD for a Compact Flash card so it's probably the fastest clamshell of the world...<p>For basic tasks (homework assignments, simple image/video editing, light browsing) it's surprisingly usable! The only downside is that I had to create a separate, unsecured WiFi network because the original Airport card doesn't play nice with modern security protocols. Oh well.
Apple 30" Cinema Display (2560x1600, 60Hz, dual-link DVI) that I bought in 2005 and have lugged around with me to jobs and homes since then. Still works perfectly.
Not sure if this counts but I still have (and occasionally play with) an Atari 2600.<p><pre><code> For you younglings, that piece of hardware is almost 40 years old.</code></pre>
Might not be as old as some others as I have throughly modernized this January but <a href="https://github.com/ddev/git-blameall" rel="nofollow">https://github.com/ddev/git-blameall</a> is very useful: this is a tool similar to git-blame, but it shows every line that was ever in the file, along with information about when it was added or deleted.