I've found working/fixable laptops, laptop chargers, cables, TVs, monitors, and space heaters to be the easiest things to give away again once I pull them from a dumpster.

Cables and converters and little USB devices like hubs are also pretty easy. Lamps and power strips/extension cords too.

I've only done a few desktops, they went but I don't know if there's the same demand.

RAM and hard drives go a long way towards making the task of fixing laptops easier/cheaper since people often pull those parts before binning them. The time I found a stack of wiped laptop hard drives enabled a ton of free computer rehabs.

As others said, you may need to feel out whether people are going to use your bins as a way to dispose of damaged things they normally have to pay a fine to throw away - my local Free Group recently had a problem with people 'offering up' broken CRT TVs, air conditioners, and even refrigerators without telling the recipient (conveniently passing the burden of the fee and disposal logistics from households that could afford to buy replacements/upgrades to ones that were relying on free groups to get their appliances). Then again, I think I'd watch to see if there's a problem before preemptively trying to lock it down and possibly making the system worse overall.

I've currently got a giant box of various working laptop chargers (a company trashed their entire supply of loaners). I've been thinking about building some kind of outdoor free library (similar to the ones for books) with a bunch of cubbords sorted by brand, but need to figure out a decent location where it can live.