Typos on big news-pages, in headlines especially. It takes away so much credibility.
Oh, man, I hate that too. It makes it look like amateur hour. The Atlanta paper has gotten so bad about that. I guess that's what happens when you lay off most of your staff.
Also: when they let something go out on the web with a headline that reads something like "We need a headline here" or a photo caption that says "caption goes here". And don't notice for hours.