How to prevent plagiarism of my papers? I have recently discovered that several of my papers have been plagiarized in order to create one paper, and that this paper has been published at a conference. I informed the organizers of the conference and the editor, and there is now notice of violation attached to the online version of this paper, so this problem has been solved. 

However, I came to know this paper only by accident (someone contacted my co-author, and told him that this paper looked a lot like ours), and potentially, we could have missed it. So my question is: are there some techniques I could use to detect such cases? 

I don't think that it's possible to detect all cases in general (because sometimes, it can be hard to distinguish between inspiration and plagiarism, and I would actually be quite glad with being a source of inspiration) but can I at least detect the most blatant ones? (in this particular example, 3/4 of the paper was actually a copy/paste from ours, and they were citing some of our other papers). 

Note that as a completely childish and probably useless reaction, I've actually stopped putting my papers on my webpage. I doubt it can solve the problem though, but at least I felt like doing something :)
You've handled the conference plagiarism very well.

But then you say you've stopped putting your papers on your website: and I'm afraid that that is completely counter-productive.

It would be far more helpful for editors, reviewers and publishers to have your papers on your website, indexed by all the usual search bots, and clearly copyrighted and time-stamped. That makes it easier for them to spot duplicate content, early on.

The point of publishing your work is to get it disseminated. Very many journals allow authors to host preprints or similar on their own university web pages: do so. Get your stuff circulated as widely as possible. That gives you the best chance of other plagiarism of your work being spotted early on, in the future.