Synchro Rev Match is ranked no. 8
No. 8
YouTube - Nissan 370Z Synchro Rev Match Transmission 01.02.09
Name: SynchroRev Match
What it does: Matches revs to road speed on downshifts on a manual transmission, essentially mimicking heel and toeing.
Extreme Example: The 2009 Nissan 370Z, the only car to employ the system.
Why it's useful: Heel and toeing is one of the more complicated driving skills to master, but it seriously boosts smoothness, reduces wear on transmissions and decreases the likelihood of spinning while braking hard for a corner. SynchroRev Match not only allows driver who can't heel and toe to reap its benefits, but by performing perfectly matched shifts 100% of the time, it'll be useful to people that can do it themselves too.
Source:
The 25 Most Useful Car Technologies