There are only a couple that have screwed me directly, but many others that I tend to avoid for other reasons.
I bought a "refurbished" iPod directly from Apple, but it didn't charge. After several weeks of jumping through tech support/cust. service hoops, despite my clear explanations why those hoops didn't make sense (they made me jump anyway, because I owned a PC, it was the problem), they finally admitted the iPod should be replaced. I had to point out more obvious facts to make that happen, I placed the order 2 weeks earlier yet the warranty expired 2 months earlier, then we cross shipped. However, the only method they had of informing me where to drop off my package led me to a DHL drop box that it didn't fit into! Holy crap I hate those scumbags.
AT&T, the very week they took over Cingular, mysteriously credited $300 on my account. But they corrected it twice. So my bill said I owed ~$340 instead of $40 and every cust. service call resulted in transfer to the next level up 3 or 4 times. Each ended with the person admitting it made no sense, but they'd have to investigate more.
Plenty of other just stink so I avoid them. Comcast's definition of service disconnection doesn't include completely disabling Internet service, and they billed me for a month when my service was still "active".
I rarely buy music because the only advantage CD's have are audio quality, but sadly it's been intentionally lowered as a marketing move.. and trying to fix it got customer complaints.
Starbucks is pretty bad. When I'm in a hurry or not paying attention and mis-pack my grounds while making espresso, it still comes out better than the burned crap Starbucks consistently achieves. I went to Starbucks with family then to a little stand we happened to drive by, and my family noticed it made the car smell better
I have the feeling that every large company has screwed somebody over; it's only a matter of chance or time before any big corp goes onto your blacklist. I could come up with a much longer list of good experiences with local and/or small companies.
edit: Oh I totally forgot Old Chicago! The vast majority of their serving staff is great and very friendly, so I still go all the time. The premise of their business is nonsense. They're not from Chicago, they're from Denver. Guess why I know this. After complaining about different beers each visit, even trying different glasses thinking wash soap was getting left on somehow, I stopped ordering beer. A couple weeks later, a server who knew me said a high up manager had visited from Denver and noticed something was wrong with the beer. It turned out something in the delivery had grown mold! My complaints never got the dipshits to check, so they'd been serving moldy beer to all customers for weeks! Also, their one bad employee almost punched me, served alcohol without checking ID, and was promoted to become a regional trainer! Sadly, I'm on my way to Old Chicago now.