An Apple wireless mouse (the early single button type) for £3.50, works.
A Pentax Z70 35mm SLR body that seems to work OK and supports autofocus, so I'm adding it to my pile of 35mm cameras I can use to test lenses. £3
A 52mm skylight filter and rubber hood for £1
A Casio fx-9750G graphics calculator with instructions for £3
The colour version of that, the fx-9850GB Plus, without instructions for £2 - both working well, unfortunately not the models with USB.
An iBook G3 and charger - looks like the charger is working but the iBook isn't - for £14; might be fixable, and the charger is very sellable.
A 60w magsafe charger with a damaged plug for £3 - looks like there's more wrong with it, since it doesn't work at all, but might get a pound or two for spares / repairs
Unknown at present
A Dymo business card scanner for £2 - I'll try it out tonight.
A remote control SCART / audio / video / optical switch box for £5 - really don't feel like messing around with SCART etc. today but ought to be useful if it works - this one's for me, not for selling.
A JVC video capture box which I was hoping might be suitable for backing up video tapes but the impression I get looking on line is that it is something weird that only works with JVC editing equipment - but they seem to sell at high prices so I ought to get my £2 back, even untested.