[julie_m]

There used to be a distribution called "Damn Small Linux" optimised for older hardware, but even it got out-of-date. It's probably still available, if you search hard enough.

Besides that, two uses spring to mind immediately, for an older laptop with limited computing power by today's standards:

1. A "thin client" -- basically little more than a simple Xorg Server, allowing you to run apps on another machine with plenty of computing grunt but no display server of its own, while the laptop just deals with the graphics end of things. (The "remote brain" could even be a Raspberry Pi 3 .....)

2. Retro gaming; either DOS-based, or through some sort of emulator. Besides the usual ZX81, ZX Spectrum, Vic-20, C64, BBC and Amstrad machines, there is emulation software available even for less well-known platforms such as the Dragon 32, Oric 1 and Texas Instruments 99/4A.

If the motherboard is just too slow even for that, some laptop display panels can also be repurposed as general-purpose composite video monitors, using driver modules available from The Usual Places online.