There was a segment on the Today Show yesterday morning that reminded us of something many of us will have to deal with at some point in our lives: hiring movers. The Today Show segment (sorry, there doesn't seem to be a corresponding article on their website) detailed the perils of choosing the wrong moving company; companies hang on to people's furniture if they don't pay, or just drive off with a truck full of all of their worldly possessions. There was an interview with one woman who was given an estimate and then, when the actual cost far exceeded the initial estimate, she couldn't pay and the moving company confiscated her things. She had to sue to get them back.
The good news is that it's actually illegal for companies to charge more than a certain percentage over the initial estimate. And an article from WNBC in February says that New York State is taking action to crack down on moving company scams such as the ones described above.
Naturally, though, the goal is to keep from getting scammed in the first place. We recommend doing your research. Ask your /co-workers for referrals, call at least three different companies for estimates, ask a lot of questions.
Manhattan Users Guide has some moving company recommendations and posters on the Gothamist Forums discuss movers for small jobs and interstate movers (with the recommendation to ship some of your stuff instead of hiring people to move it for you if you're moving a long distance).
Related: Ask Gothamist on the hazards of moving in NYC.