Faster promotions, bigger bonuses, more flexible hours. Small companies do what they can to keep employees, says a survey by Sage Software Inc. One thing your peers avoid, however, is counteroffers. Half of big companies will match an offer to a job-shopping employee, says Paul Dorf of Compensation Resources Inc. But just 27% of small ones do. Why? Entrepreneurs, say the experts, think quitting employees have betrayed them--something money can't fix.