Tiny rice lights
Tiny little LED lights on silver wire.
Powered by two AA batteries, they can be placed anywhere as you don't need to put them near a plug. The battery box can even be used outdoors as it has a weatherproof seal.
Hang them round a picture frame, along a mantelpiece or weave them through flowers, they can even be used outdoors.
They've got a timer – you can switch them on permanently (until you choose to switch them off) or you can switch them on for 6 hours and then they go off for 18 hours before repeating.
40 LEDs on 3.9 m of wire overall with a 30 cm lead in.