Commuter / gravel trail bike:
* Generator hub + front light
* 400L Di-Notte rear light + extra blinkie as backup
* red blinkies on bar ends
* Garmin 305 Forerunner mount + speed/cadence sensor
* 2 water bottle cages
* Back rack with rack bag; up to 2 waterproof panniers; quick-clip to add seatbag if I'm not using the back rack.
* Frame pump
* Locking: some combination of nothing, U-Lock, thick braided cable in rack bag.
* Trainer computer when in trainer (includes current, high, and average watts.)

Road bike:
* 400L Di-Notte front and rear lights (remove batteries for day rides)
* red blinkies on bar ends
* Garmin 305 Forerunner mount + speed/cadence sensor
* 2 water bottle cages
* M, L or XL seatbag with blinkie.
* Frame pump
* Locking: nothing yet(?)

I also need to set up the bad weather / winter / errand mountain bike. So far:
* Cheap front light
* Blinkie
* 1 water bottle cage
* quickclip to share seatbag with regular commuter
* water bottle pump
* 1" braided metal cable (mounted to the other water bottle cage bolts)
* back rack
* Plan to get: Garmin Forerunner 305 mount + speed/cadence sensor; sidewall generator (hub generator?) to run front and rear lights, possibly a bike trailer.

Seatbag always has: multi-tool, tube, tire levers, patch kit, tire boot, presta-to-shraeder adapter, extension for presta valves, wipes. Key/ID/credit card/money either in here or in foot pouch. Sometimes phone, extra food, spoke wrench. I really should put in duct tape, disposable gloves, chain links/linkers, gauze, tweezers, and iodine...

I know of at least two sources for rear tailights: Nashbar has a model (on sale Tues/Weds for 72% off an already cheap price), and Peter White Cycles has a hub generator front / back light duo where the back light functions as a taillight.

I love the look of the mountain feedbag!