Google cache is my friend (and your ennemy)
So your site has been almost entirely ripped off by some trolls but before long, the infringing pages have disappeared in limbo. What do you do? You invoke the Google cache and use the advanced search facility to narrow your queries to a specific domain. Then, using some trademark or name you own, you nail down the culprit (and let the dogs loose, as many have kindly suggested).
For example, Sogeti is a fully-owned subsidiary of the Cap Gemini Ernst & Young Group. A Google search for "sogeti site:www.odonnell.ee" gives two results that led to something 48 hours ago but not anymore, however let's see what's in the Google cache and compare, for example, this to the original. Isn't that funny, two different companies, having the same chairman (Google on "serge kampf site:www.odonnell.ee" gives interesting results too) and releasing exactly the same financial figures on the same day? Those are only a few examples, I have a printout of 933 pages, basically every single HTML page we had online around March, on which about 10 were not copied straight from our site (at that scale, I really didn't bother to count anyway).
The Google cache, in this particular case, is for the plaintiff both a benefit and a problem. A benefit because even so the infringing pages have disappeared, it is easy to bring them back to materialize the infringement. A problem because when 70% of your visitors who come through search engines do so from Google, they may as well be diverted to (highjacked by, actually) the pirate site. Let's invoke Google another time on something our clients may search for (it may sound boring and irrelevant, just trust me on that one): "IT Global Development Center". Surprise, the pirate site appears first with two results, before the legitimate page which makes it on the third place only! How come? Simple: the copy is more recent than the original, so Google gives it a better rank.
Hopefully, the Google cache will eventually be cleared, stopping this mess (and breaking most of the links on this story, sorry if you came here too late). After which, nobody can tell you're a dog.
This is what I like with the web, each time you are tempted to become blasé, there is something new that tells you you haven't seen everything yet.
On a side note, if you think that intellectual property (or copyright) is theft, think twice. When I express my feelings about music majors or the DMCA, I am not challenging those principles, but the lack of balance and threats that IP extremists are imposing on everyone, our commons and innovation in general. If you cannot see where the theft is in the above post, you are blind, or naïve or may be you run a consulting company in Tallinn, Estonia.