What do you do with old memory cards?

I believe that for most people, once you have 600x or 32Gb/64GB card, you won't use your old 133x, 300x, 8GB card.

So, what do you do with old memory cards that are low in capacity or slow in speed?

For me, I carry them most of the time but don't find the need to use them because new cards have enough storage.

When I sell used gear, I usually bundle old cars so I can get rid of them.