For my best friend's 50th I did her a big bag of spoof pressies including
Sanatogen tonic wine, Tena lady, a plastic rainhood, a hairnet, a magazine for oldies, a pack of haircurlers, a Max Bygraves LP, a beige cardigan, beige bedsocks, a beige headscarf, Steradent, Werthers originals and a variety of leaflets for stairlifts, mobility scooters, Saga hols etc etc. A lot of the stuff cost me pennies from the charity shop.
Are you still friends with her, mrs_overall - or rather, is she still friends with you? I'm going to be 50 this year and REALLY not looking forward to it very much!
I'm afraid that I have no original ideas oopsydoopsy, why not get her something that you know she'd like!!
I think you have to make light of it (those pressie ideas are great) because for some reason girls just don't want to be fifty! My friend turned 50 last June, had a lovely big party, loads of lovely presents, and she is still bemoaning the fact that she's 50!!
Maybe you could do the opposite thing and buy her stuff that usually young girls like, e.g glittery nail varnish, sparkly hair clips, stripey socks/tights, cuddly key-ring etc.
I'd better just add that as well as the spoof pressies for my friend I also bought her 10 horse riding lessons as it was one of the things she's had on her wish list for years.
We have a long history of doing amusing things for each other on significant birthdays. For example, for my 21st she told me to get glammed up for a big night out. I was done up to the nines and ended up being taken to the wrestling at Leeds town hall, followed by a fish&chip supper!
You could use some of the ideas above, to get 50 cheap and cheerful presents, and put them all into an old box, tied up with a huge ribbon. Hairnets, hair grips, the ads for various stairlifts and so on. Have a look round your house - pop a loo roll in, magnifying glass, a "denture" box, old woolly gloves, socks.....
Hope she has a laugh anyway.
How about some of the above plus a voucher for a massage, facial etc?
There is nothing good about reaching 50 (except for the fact that it is better than the alternative!) so a bit of pampering might be just the ticket.