I found some interesting ideas for mesecons. I know my earlier ideas were bad, but these ones, I hope, are better.
The first things would be an SCR and an SCS.
The SCR (Silicon Controlled Rectifier) is like a diode, except for power to go through it, it needs a shock of power from the gate. When power goes through the gate, the gate doesn't need power anymore, and the SCR will act like a diode until the main power turns off.
The SCS (Silicon Controlled Switch) is the same, except it has another gate called the anode gate. This turns off the power in the same way as the gate turns it on.
A third gate could be made with only the anode gate and no normal gate, and power would always get through until turned off with the anode gate. As far as I know, this doesn't actually exist, so I can't show an abbreviation.
An interesting thing about these logic gates is that they can have multiple gates and anode gates.
Manually made gates
An LED would be useful. It would be a diode and a flow sensor in one, plus the fact that it can come in many colors. A small lightbulb would be another good flow sensor, and it wouldn't have a diode built in. The main difference between these and lightstones would be that power could flow through the lightbulb and the LED as opposed to just stopping like the lightstones.
A useful thing would be a switch plant. The plant would have two ports for producing power and would act similarly to a blinky plant. It would switch from each port every three seconds. This could be made with two blinky plants, but it is extremely annoying to have to synchronize them properly. Delayers don't work for this, since they take time to turn off.
I would like a capacitor similar to this:
The capacitor would be charged through one wire, and once it is charged, the light in the corner would turn green, and power could be released by turning on another wire, by clicking on it with the mouse, or automatically. I don't really know how this would be done. Different capacitors could hold different amounts of power, like one second, three seconds, five seconds, ten seconds, a minute, etc.
There are solar panels, but what if there was a lunar panel that makes electricity at night? You could make one with a solar panel and a not gate, torch, or an xor gate, but those aren't compact. A lunar panel could be red or something and crafted like this:
[--, --, --]
[solar_panel, mesecon_torch, mesecon]
[--, --, --]
A different craft could be used. That one is just a sample of what it could be.
Lastly, I would like a photoresistor. When it has light, it lets power through. When it is dark, it doesn't. Similar to the solar panel, I would like an inverted one. It could have a similar craft and be called a photoconductor.
I hope some of these things can be implemented into mesecons.