Redstone Circuitry - Resistors?

No; redstone can be used to emulate logic gates, not electrical components. There is no analog to any electrical component, nor any use for them.

If what you want is to slow down/delay the signal (which is not what resistors do), you can use a redstone repeater.

You can use a Redstone Comparator to produce a desired signal strength. When set to subtract mode, the signal being produced out the front will equal the back input minus the side input.

Therefore if you have a repeater directly behind the comparator (15 signal strength), and a lever with two pieces of dust going into the side (14 signal strength) the comparator will output 1 signal strength.

If the comparator has two side inputs, it will simply use the most powerful one.