2003 Buick LeSabre Custom....65K miles...100K Miles on engine.

This is going to sound quite strange, thus here I am. No SEL for any of this. Car was OK until one day when it would misfire and shutoff at various speeds, etc. Then the Traction Control, Brake and ABS idiot lights came on. Drove for several weeks that way until an ICM was sourced. Replaced the ICM, spark plugs and wires. Car was parked on the driveway and the next morning a large amount of brake fluid was under the car and dripping from the oil filter. I could not locate the leak...for hours I looked. Brakes still worked fine. Filled res up to MAX line. Next night, same thing. Check fluid, low, refill. Next night, no fluid. Next night, no fluid. idiot lights are still on. Then no acceleration power...idiot lights still on. Replaced the Catalytic converter. Runs very well now. Brake system idiot lights are still on but brakes work great, even wear. Then two days later, get in car, start up and NO IDIOT LIGHTS! Brakes still work fine and of course traction control works now. What the heck?

Thought about a extremely small pinhole leak somewhere on a brakeline shooting fluid onto some area of the engine causing dripping from the oil filter. Can't find. The vlave covers do leak and so does the transmission...somewhere. I had a car once that had a pinhole leak in a line and I lost all braking so I am not understanding something. If brake fluid is on the groundthen there is a breach in the system somewhere and the brakes should not work since the fluid will go the path of least resistance...the hole.

Any takers? Exorcism? Stake burning? Big steel stake through the motor?

If the trac off/abs/service vehicle soon lights are on, it could be a bad wheel speed sensor, or a problem in the connection at one of the sensors. If its just the "brake" light on, then its probably just the sensor telling you that it'* low on fluid.

Are you sure that its brake fluid on the ground? If its leaking that bad, then you should notice it in the pedal. I don't think its even possible for brake fluid to be able to drip off of the oil filter.. The closest place for that would be the reservoir area, or the ABS module..

Brake light could have come on due to low fluid, then once you start keeping the reservoir filled to offset the leaking, 50 starts later the diagnostic trouble code clears itself and the light goes out.

Seems like an odd spot for brake fluid to be leaking, but the fact the brake reservoir level is dropping indicates that is what it is. Put some clean cardboard under your car overnight and observe where the leaks are. If you see fluid dripping, put some sort of clean container under the leak to capture some fluid. Ideally you want a margarine container or something like that, because it will be easier to see the fluid color in a white container. Is the fluid reddish, or brown? Have someone pump the brakes while you are looking under the car to see if that speeds up the leak.

If you can't track this down, I would take it into a shop. You don't want to risk losing brakes when driving.

All three lights. I was thinking the wheel bearing assembly with the sensor but the problem magically went away. Fluid was clear so not engine oil, or tranny fluid or power steering fluid. Plus the brake reservoir was low on fluid. The lines do run to the front wheel and both rear wheels on the passenger side where I found the puddle plus I could see how a pinhole stream could shoot on an area just above the oil filter. Perhaps has anyone else had brake fluid leaks from any particular areas on the brakeline route? Maybe the pinhole clogged itself? Can extreme errors to the ECM (loss of feedback from the ICM, misfires, etc.) also cause errors in the ABS section? Since traction control is also a function of the tranny, can extreme tranny errors cause the entire traction control system to go offline and light the idiot ligts?

I don't think the traction control is any function of the trans. Its a function of the ABS system, and to some extent, the PCM.
All three lights suggest an ABS system problem (wheel speed sensor, bearing/hub, wires, etc).
It sounds like you're getting really frustrated with it all. Best idea is take it to a shop at this point. Even once idiot lights go out, sometimes the car will store pending codes that can be read. Also, its a lot easier to inject some UV dye into the suspect system and track it back to the source. If they can put some dye in the fluid, and there is a pinhole leak, it will be a lot easier to find that way, than all you're putting yourself through.
The only place I can think of that might do it, is at the ABS controller, if I remember right. If it is leaking at your ABS module up at the front, that might trigger the trac and ABS lights. If the lights go back on, and it can be scanned for ABS codes, it might point back to a central source, rather than an individual line.
If I had the problem on my 04 LeSabre, I'd probably have a shop look at it by this point. I try to do all I can myself, but at some point, a fresh pair of eyes on the problem may solve it a lot quicker.
Remember that brake fluid absorbs moisture. Once you get this all figured out, I would definitely get the system flushed.