lol....you guys are funny! gettin back to the original problem: after i bought a new battery from PepBoys (didnt see that Wal-Mart tip till AFTER i bought it, natch!) i had ANOTHER issue! i posted a new thread here:
https://www.mazdaforum.com/forum/mazda6-20/tranny-skipping-21651/
please take a gander @ it!!!!
Thanks everyone!!

 

I have a 2004 Mazda 6 wagon, I have had to replace my battery every year, I can pretty much count on about 12-15 months service and my battery will take a crap. We have been very diligent to treat the terminal post with an anti corrosion spray, but still, the car just eats batteries, and when it decides to go, it will give you no warning.

 

The battery in my wife's Vibe just died like that... no warning at all. She had just parked the car, realized she didn't do the best parking job so she went back to move it up a few inches. Nothing. Dead as a doornail... as far as the starter was concerned at least.
I had one do that to me a few years ago too. It seems that's the way modern lead/acid batteries are most times.
As far as eating batteries though, it sounds like you either have a slow draw that the charging system cannot overcome when the car is running, or the charging system itself is in question. It might be as simple as a weak diode pack, or that the voltage regulator doesn't kick in soon enough, until the battery/available power is very depleted.
Personally, that's where I would look first. There should be no reason the car goes through batteries like that by design.

When driving at night, do the headlights seem to gradually get very dim, then all of a sudden bright again?
If so, voltage regulator. If not, probably a diode pack.