Over the last couple of months I dove into the vintage Macintosh community. In the process of restoring a Macintosh SE/30 and waiting for a Macintosh Quadra 700 to arrive. I've collected a few somewhat rare upgrades, including a DayStar PowerPro 601 that is somehow new in the box. This is a card that can go into the Quadra 700 to add a PowerPC 601 CPU at 100Mhz.
But the things I'm most excited about is the new hardware the community makes to work with these old computers. There are devices like ZuluSCSI and MacSD that let you replace the spinning hard drive with a solid state device that uses an SD card for storage. There is PiSCSI which attaches to a Raspberry Pi and emulates multiple SCSI devices, including hard drives, CDROM, floppy and ethernet.
FloppyEMU acts as a SCSI floppy drive and lets you load up a bunch of floppy images and swap between them without having to make actual floppies.
ADB-USB Wombat lets you use an ADB keyboard with a modern computer, or a modern USB keyboard with an ADB computer. I'm typing this on an Apple Desktop Bus Keyboard (AKA Apple IIgs Keyboard) on my M1 Macbook Pro.
And I'm waiting for delivery of a modern clone of a MicroMac Carrera04 accelerator with an adapter and ethernet for my Macintosh SE/30. This puts a 68040 40Mhz CPU in my SE/30, which normally has a 68030 16Mhz CPU. These accelerators are hard to find so someone on the 68kmla.org forums reverse engineered them, and makes small batches of clones. I had to source my own 68040 CPU, as those are getting harder to find, but I have one on the way.
These old Macs also have a unfortunate tendency to self-destruct if not looked after. The motherboard batteries can leak and basically destroy the inside of the computer. And the old capacitors do their own version of this. So both need to be replaced. Because of that, there are also full logic board recreations for several vintage Macintosh computers, especially the compact Macs. Since the original logic boards have some hard to find parts and some proprietary apple ICs, it requires a donor board, de-soldering various bits, and putting them on the new board.
Much of this stuff is happening in plain view either at 68kmla.org or tinkerdifferent.com