 He says that will give them some immunity and they'll be able to get the new booster shot later in the year. Michelle Morello, WTOP News. Have you heard of these niche job sites? There are hundreds of so-called niche job sites, smaller sites that cater to a particular segment of the labor force. Here are five that might be worth a look. Sales gravy caters to jobs for sales professionals, from entry level to management and executive roles.