Mediacom
My favorite is Mediacom -- they (without telling customers) switched to a 3 strikes system. (They shut off internet on 1 and 2, then on 3 expect people to come in and sign some contract.) The nice part is, the IP<->customer database is SCRAMBLED. So... a few years ago....
My internet gets shut off. I called in, and they say it got shut off over some file or other. I did torrent it, so I said fair enough, I won't torrent and it was turned back on.
Few weeks later, Internet gets shut off again. I called in, they didn't claim what file it was shut off for. But I said, well, OK, maybe something "crossed in the mail" from earlier. They turned it back on.
Third time, I get a piece of mail (misaddressed -- supposedly I was supposed to get something in the mail the first two times too.) It claimed I tried to distribute wrestling (nope) and the IP address listed was wrong (I have a log of the public IP addresses I had, and it matched none of them.) In fact, the address they listed was for the Des Moines market, over 150 miles away. Hmm...
I came in. They wanted me to sign something. I read it and found it only applied as long as I maintained internet service (otherwise i would never agreed to the ridiculous terms listed). So i signed it, let them waste their time faxing it to their central office, then handed over the cable modem and cancelled on the spot (so the contract only applied for about 45 seconds.) They looked flabbergasted! At my friend's advice (who at that point had an ISP and so directly competed w/ Mediacom) I *didn't* tell them their database is all screwed up -- I figure a company that cooperates with MPAA/RIAA when they don't have to DESERVES to lose customers if they can't even make sure they are doing it right. Sure enough, at my workplace (about 30 people) I started hearing 2, 3, complaints a month from people who were not torrenting a thing getting their service randomly shut off, and several did cancel their service (they never got to "strike 3" they just got sick of the internet randomly failing for false reasons.)