It’s no surprise that the Nielsen Company has reported a 20 percent year-over-year increase in visitors to job sites. Yes, more people are unemployed, but job sites offer a quick (and free) way to find out what’s available in your industry. When responding to an online posting, use the language that’s in the job description; the technology used on these sites scans résumés and ranks them by matching key words. The following sites have been recommended by the top human-resource specialists and career counselors in the field. Happy hunting!