Mods on FZ6 there isn't much 'bolt on' customization, a lot of it is finding 'compatible' parts and 'back yard fabrication'. However...
Cosmetic:
Naked conversion (vs-1 or vs-2 headlight kit) (sold by a forum member)
Cut down tire huggers
Carbon fiber trim/pieces (3M sells a CF adhesive, very nice, search for thread its there)
PUIG raised windscreen (convenience and cosmetic)
Belly pan
Rear seat cowl
Painted engine (also a thread on this)
Painted frame (another thread on this)
Painted forks (another thread on this)
Dual Headlight Mod (kind of performance) (also a thread on this by BD43)
HID Projector kit(s) (multiple threads on this)
LED Brakelights
LED turn signals
Body/under glow LED's
Footpegs
Performance:
New Exhaust (many threads on this)
Drilled out stock exhaust (a few threads on this)
Power Commander III (there's another brand, I forget what--also multiple threads about it)
Gear indicator
Sprocket size changing (affects fuel economy, speed, acceleration, etc--should be threads about it)
Chain type
Radiator fans/guards
There's lots you can do, it all comes down to what you want. Are you wanting it to look better, or perform better? Or do you have the capital to do both?
Look around on forums, I came into these forums thinking I couldn't do anything to the bike. Now I can't figure out what to do first. Lol

Mud