Values
In many companies - especially smaller ones - bringing on a new employee can feel like adding a member to the family. Knowing that he or she will get along with their co-workers is extremely important. Companies - big and small - are building a more open, friendly, and identifiable culture. Very rarely will interviewers want the absolute best candidate IF that candidate is hard to be around. Skills can be honed, but values and behavior is much more difficult to change.

Attitude
To borrow an old sports adage, "Hard work beats talent, if talent doesn't work hard". Maybe it's trite, but that doesn't make it less true. Employers want to know that you take pride in your work and are, not only willing to learn, but eager to grow as a professional. Generally, companies don't want to hire a "full-book" so to speak, they want to know you are not coming into the the interview (or job) with a know-it-all mentality. No one truly knows it all, so don't even bother pretending.

Vision/Ambition
This is often a place that employers separate the wheat from the chaff when vetting candidates. They typically don't want someone who views the position as 'just a job' or 'just a stepping stone'. Employers want someone who is interested and invested in the company itself. Just don't let your ambition get too far beyond the scope of the position you are being interviewed for.

Environment
Different companies have vastly different work environments ranging from open and collaborative to cubicle laden and shut off. Not everyone can thrive in every environment and employers are fully aware of it. For instance, some personality types are easily distracted in a fun, loud, and creative office, while others feed off of it. If a candidate has experience and has excelled in a similar environment to what the employer offers, they may get a leg up in an interview.

The amount of weight put into these aspects of fit will certainly differ from employer to employer. When searching for a job, doing a little bit of research, choosing companies with clearly laid out culture, and crafting a resume to match that culture can be the difference between an applicant and new hire.