As an example, I use the Nostur client on iOS a lot and when you zap it shows you the current USD exchange rate for various amounts. You can set a default zap in sats, but I would love to be able to set a default zap amount in USD and then the client just initiate a zap for the corresponding number of sats. Curious what others think too. 

https://image.nostr.build/507a60fe5d762fed76395675db9d4b908b480cb312e6e8d54f2810a301dec7e6.jpg