Making them feel like they are part of a team is very important, and especially noticing and acknowledging when they work hard or went the extra mile. For example - 'Joe' stayed in all weekend to finish something important for the company and, while it was very frustrating at the time, his boss gave him a gift certificate for a nice restaurant to reward him for his hard work. A little acknowledgement goes a long way in keeping your employees motivated and happy in the long run (aside from the yearly review/salary increase).