I'm Dave. I grew up with an IBM PCjr in the house and since my parents recently moved, I acquired all the old hardware from them.
Now, I have the jr, display, and the old chiclet keyboard (can't seem to find the normal keyboard...I know we had one...oh well) and several sidecars and carts. I have an MFM sidecar, but alas the old MFM drive box got thrown out when the drive stopped working a long time ago (not that it'd be easy to find an MFM drive anyway). I have 2 PSU sidecars, 1 MFM sidecar, 2 parallel port sidecars, and 1 memory expansion sidecar.
As far as other peripherals, I have the direct-connect IR mouse and IR mouse reflective pad, and a joystick.
I have the modem installed in the main chassis as well.
As far as I know, it's the regular old 8088 in there...not the V20 or anything modded like that.
So, I will be ordering a 5.25" drive for my modern PC so I can write floppies (I used to have a nice one, but that got thrown out it seems...only have a 3.5" floppy in my bin of old stuff). After that I'll play around with booting DOS and hopefully I'll move on to a jr-IDE setup.
As for me personally, I have a BS in Computer Engineering and do a combination of electrical design (most familiar with CADSoft Eagle) and embedded firmware for ARM CPUs. I am looking at the possibility of developing an Ethernet controller based on an ARM CPU and writing a packet driver to support the old DOS systems. It wouldn't be a stretch to further manage a wireless Ethernet adapter on the same module.
Keep rocking the vintage hardware!