I'm adding to this thread since it's been inactive for awhile, and my question is very simmilar...
I've got an interesting scenario in my truck. (4runner actually, lots of sound space!

I've recently purchased a 3 way eclipse set (5.25Woof, 2"Mid, 1"Twt) and plan on adding these to the front stage via a ton of fiberglassing. I've also replaced the two 4" factory's in the front/lower dash by the doors with proper two-way Eclipse upgrades (25rms running from the 21rms deck), and get a nice low stage from them. To continue, I've fiberglassed two custom formed boxes for mounting on the rear ceiling to help equalize the stage slightly, and have Q-series MB Quarts in them.
So now technically I will have 10 speakers in the front (If you count the coax's as 2 drivers each with neo tweets in them), and where should I put them!
I saw a picture of someone who had fiberglassed boxes for his Mids and put them on the dashboard in the corners. I thought of doing this with a mid-tweet set for esach corner, and mounting the 5.25's in the doors angeling upwards...
Any ideas anyone?? what would you do??