Redstone - memory devices

[Romedy]

I've had an idea and am working on the blueprint but am concerned it will require a memory array of some sort. Since a lot of the tech I use is old and outdated, I wanted to ask folks for ideas.

I can build a traditional RS-Nor latch array
I can build memory arrays involving 4 pistons cycling blocks around (Like in a digital clock)
I can build repeater arrays that use repeater locking. (Basically a repeater T-Flip in sequence.)

Are there any memory arrays using hoppers, or new tech not listed above?