All brilliant ideas, thanks, although I'm not sure she'd be safe with lighter fuel heated handwarmers (there are other types though and I think she'd love them, she's often really cold when she comes back from lunch club).
I'm definitely going to have a look at some warm nighties. I agree about the hand made presents, ina, but I know she's spent a small fortune on us. A scarf and hat, compared to the microwave (which I didn't want)
and a slow cooker (which I did want), seem paltry. We have got her a few bits of biscuits and crackers (she lives with us so tea is on demand

) as she likes a nibble with her cup of tea.
I'd love to get her a simple cd system, but I think that would be a brilliant 90th birthday present - she loves music, particularly opera. I had thought about contacting the remaining members of her family to get stuff to make a photo album for her birthday but then I'd completely forgotten about it. I'll get on to that straight away.