Fuel Jugs

Acerbis 4 Gallon Dump Can

Dry Brake Quick Fill Systems
These are really the way to go. There much faster and cleaner than the budget alternatives listed below but they cost significantly more money.

Acerbis makes my personal favorite as it works with stock gas caps/tanks, has good handles and dumps 2.6 gallons in 8 seconds on fuel tanks having 2" (39.5mm) or greater diameter openings. Larger attachments are available seperately if faster fuel transfer.

On most street bikes you may have to modify the stock gas cap so that it opens a little wider to make room for the Acerbis dump can with the standard 8 second tip.

Remove the 4mm alan screw at the end to disasemble when replacing o-rings, etc.
Acerbis USA
P.O. Box 2030
Sun Valley, ID 83353

Acerbis O-Rings
The O-ring that wore out on the tip most closely resembled an R23 (ID: 30, Section 3.5) from my metric O-ring kit. Except it was thinner. I measured the o-ring grove on the tip at ~3.15mm wide and ~31.8mm in diameter. The wall thickness of the o-ring Acerbis sent me was ~2.6mm. That might be an AS568A -124 or smaller.
satoriseal.com - An Introduction to O-Rings
allorings.com - O-Ring Sizing Chart

Budget Quick Fill Cans
Not quite as fast as the options listed above but, not too shabby for the money. The Hunsaker is my favorite for the money. It's faster than a regular fuel jug, easy to hold and relatively cheap.

Hunsaker 5 Gallon Dump Can

The downside of the Hunsaker jug is refilling the jug itself. Unlike a regular jug with it's large opening (when the cap is off), the Hunsaker is filled by removing the cap off the vent/handle. The opening is not much larger than the filler hose itself. You also have to remember to remove the filler hose cap when refilling the jug. If you don't the fuel will just fill up the vent/handle part and then start spewing fuel all over the place (and on you).
Also, You do not turn the Hunsaker straight up like a dump can. It pours similar to a standard jug, but you can hold it at a steeper angle

-redelk at http://www.bikeland.org/board/viewthread.php?FID=1&TID=10793&set_time=1092088409