Specifically, a lunchbox. Last summer I'd put it in a book bag and carry it that way, but it was a bit uncomfortable. Plus I was on a different bike and didn't have to lean over the tank.
this year I am on an F4, and I have a bigger lunchbox.

Just wondering what other people do and what options there are?

 

Get some saddle bags. Nothin cooler than a sport bike with some big ol plastic boxes hangin off the rear seat. FJR

 

Dont know how far your traveling etc, but i got two nylon adjustable bungee straps from walmart. If you cross them and put them through a handle they hold many things down on the back. I have traveled with a small duffle bag , lunch box for short distance (2 miles to work but did fine), and it does a wonderful job holding pizza boxes.
simlar to this... http://www.off-road.com/offroad/data...p_image010.jpg

However after looking at the f4... you have posed a good question..
on my 900rr http://tinypic.com/view.php?pic=2a7ids8&s=3 if you look at the front of the back seat there are a couple aluminum like dowels that i hook the straps to, and then just to the fender on the back. However on the f4 not sure how you would make that work.. Hope i helped though.

 

I've been commuting 30 miles one way for 5 years. The best thing to use is a helmet net. Ive used bungees and they work fine if your strapping them on a backpack but they can slide enough to drop your stuff too. With the helmet net, hook the hook on the passenger foot pegs, set the lunchbox, bag whatever on the pillion seat, and pull the net up and over then wrap the back set of hooks around the undertail and hook them to eachother. There are lots of different size nets so be sure and get one that will fit tightly what your carrying. Whatever you do dont hook the hooks on the plastic hooks on the stock undertail hooks. I had both of them brake once and send my stuff flying down the road.

 

The bike I almost bought was an Interceptor, with saddle bags.

A helmet net is a great idea I hadn't thought of.

Years ago I went out with a bowling ball (in a bag) bungeed to the back seat of my Ninja. It fell off going around a corner, even with the bungees going through the straps.

 

ya I had a tire strapped with bungees once and the hooks on the undertail broke and slung the tire out into traffic. that sucked, but luckily a older man in a somewhat beater truck swung out in front of the tire and tapped it with his bumper to stop it. could have been alot worse.

 

I have a rack fitted, comes with two bags (big & small) that can zipped together easily for bigger capacity. Two clips & they come off, complete with carry handles.
Years ago I got a cheap tank bag, mainly for wet weather gear, didn't want the thing on my tank, fitted the bag holder to the pillion part of the seat (elastic stays) & just clipped the bag on when needed, easy to get on & off.