Any links back to your site from relevant sites can increase your search engine performance, which is why RSS feeds have become so popular.
A jobs widget is a sophisticated way of distributing your job content to other sites in a branded format. You can feed job content to other sites you own or third party sites to increase the reach of your jobs and boost your target audience and increase the links back to your site. This can be combined with an affiliate marketing programme where you can pay sites for driving traffic and in turn you receive revenue based on the number of clicks you feed back to other sites. This is very popular in job board aggregator models.