I don't really feel that strongly about the issue of bandwidth leeching (or "leaching" - take your pick), mainly because this site doesn't really get an awful lot of traffic, and I'm always well within my bandwidth allowance each month (oohh, poor me!).
A certain percentage of my bandwidth is leeched each month however, by people linking directly to images on my site. When people are giving MrCeri the major kudos I so deserve, I simply wave, "carry on good Sir, leech away!". But when they are re-using my images for their own evil gains, without an appreciative nod in my direction, I shake my head in despair at how low society has fallen.
It's fun once in a while to try and come up with strategies to prevent people nicking images off your site, and by extension pilfering your bandwidth. There's no real way of course to protect either at the end of the day - there's always "Alt-Print Screen" for the images, and as for bandwidth, there's always Slashdot :) Still, it's not hard to come up with strategies to thwart 95% of your visitors.
So this month I've started tinkering with some of my worst affected images, not really to save bandwidth, but just to restore a little credit where credit's due ;)
Yes, it's very childish I know, but that's the internet for you!