another useful one is <(cmd here)
It's like $(cmd here) but instead of returning the output of the command as a string passed into the arguments, it makes a new file descriptor for the output of the command and returns the path to it, for use in commands that want a file as an argument.
So for example if you want to use diff to compare your local passwd file to a remote one..
diff -u <(ssh host1 cat /etc/passwd) /etc/passwd
Admittedly I can't think of many things I've used this for outside of diff and alternatives to diff..but I've used it there a lot, like comparing the results of running two slightly different queries.
Or you'll see something equally efficient and equally performing at the same power levels..except you'll see newer gens or upgraded skus allowed to pull more power