An upgraded version of Fluid and Item Routers that would enable a higher degree of control on what goes where but more importantly how much goes where. As a downside, the Advanced Routers would require power to function (maybe 64 rf/t?) and as a result would lose 1 output side; which side you lose can be configured with an engineer's hammer (similar to capacitors and fluid pumps).

To start:
Advanced Fluid Router - in addition to directional filters, can set how much millibuckets/t are allowed through and use a logic operator of <,>,=,<=, or >=. You could also disable certain outputs via a colored redstone signal supplied through redstone wire.

possible uses: ensuring your Mixer multiblock never has too much water in it when mixing potions or other fluid like concrete, if and when it gets implemented: only output a certain amount of water into a nuclear reactor to produce steam or to evenly split produced steam into Steam Turbines.

Advanced Item Router - in addition to directional filters, you can allow only a certain amount of filtered items through using the logic operators of <,>,=,<=, or >=. Like the advanced fluid routers you can disable certain outputs with colored redstone wire signals.

possible uses: When processing a large amount of ore from an Excavator, the need to compress ore as much as possible to save on space makes the 3x3 packing mold very useful, however unfortunately there doesn't currently exist a method to only output a certain of items into the metal press autonomously; The Advanced Item Router would solve this. Another use would be with Assemblers as it would allow you to always ensure an assembler has enough materials to produce whatever its assigned to make, and would prevent an overflow of too much of 1 item. Another use would be with an Arc Furnace when trying to operate as efficiently as possible in terms of processing, by queuing multiple ores it can ensure the Arc Furnace only processes when there is a large amount of materials.

also valve pipes like what engineer's decor adds, they really need to be standard.

Would like to add: a router that lets you round-robin outputs based on ratios - like a splitting conveyor belt but configurable. Would be fantastic to be able to do something like "route every 16th item to the left, and the rest to the right". (This can be accomplished right now with a bunch of splitters/conveyors and some binary algebra, but the resulting network is complicated and takes up a lot of space.)