Another informative reply. This discussion has been very useful.
OK, spam proof Guest Book is certainly the (only) one to go for.
Now with images, it gets more complicated. Firstly, even if they are free with attribution, I don’t want to mention and link others on my site, nor do I always know who the legal owner is, as the image could appear in more than one places that I don’t even know of. Secondly, if I ask them first, there’s the risk they’ll say no or want attribution, and I’d then be in a worse position, because they’ll know about me.
As regards a pirate following the law, yes, I thought of the same thing myself, and it does sound (and is) contradictory. But it’s the law of necessity we’re all following. It’s one thing hiding behind a nickname in a board full of similar others, knowing there's no precedent of prosecution, and another sticking your neck out as an individual. It’s like avoiding torrents, not because we respect the copyright law, but because we know we can get in legal trouble.
After all, the most important Commandment is the 11th, unwritten one:
Thou shalt not get caught!
Do what you like with the others, just respect this one and you’re in the clear.
In the last analysis, we are “fair weather†pirates.