Accessorizing is a DISEASE.
SLMan - I agree that the spot that FW puts the GPS units is not good for visibility. I found that I spent more time driving the H240 sitting on the bolster and peaking above the windshield. A GPS down there would have been totally useless for me - but it sure looks dang sweet.
I think that's a great accessory if you boat along a coastline... I would definitely make that a P1. Which one is Ryan recommending? Also consider if you can get the GPS plugged in to show trim tab data, fuel flow info, etc... Kinda a cool feature.
Other "accessories" to consider.
1) What's your plans for a BBQ on board?
2) AC inverter for charging phones, laptops, etc?
3) Good quality ropes/fenders/fender covers/etc? Do you have a good achor/rode setup for the boat?
4) Watersports toys... and ways to inflate them, haul them, and ropes to tow with them. Also take a look at the Four Winns raft on the accessories site -- it's SWEET!
5) Lights. LEDs, under water, platform, cupholder rings - whatever.
6) Stereo. I'm all about JL Audio (although I just found a nice connection for Kicker gear which is making me think twice)
7) What can you get to make your wife happy? Happy wife = any boat accessories you want.

Trailering accessories... locks/couplers/straps/spares/all the stuff to make trailering easier.
9) See #7
10) Save money for gas. With a 496 HO - you'll need it.