If this has not been mentioned, I would like to see a modifiable delay and/or increment added to the chess clock (this is the digital age after all) - e.g. 5-second per move. Perhaps adjustable from 0 - 59 seconds.
The difference is that with a delay (Bronstein)- used more in US - if you don't use all of the 5 seconds to make your move, your overall time does not change. With an increment (Fischer) - used more worldwide outside of US - if you don't use all the time for a move, those extra unused seconds get added to the main time.