Forwarding a keyword rich domain name to your existing site will do nothing to increase your Google ranking or your traffic. You would have to develop a website for that keyword rich domain name, have it rank in Google in it's own right - and then have a link on that site to your main site. IMHO your energies are better spent developing your main site for that keyword. If you want to get that 2nd domain name then use something simple like Tumblr or Blogspot that make it easy to add content. A related debate on SEO forums is whether to put a company blog on the main site or on a second site. I believe the majority opinion favors putting it on the main site and putting your SEO efforts into one site.
I suppose if you install 301 redirect on your new domain name you will improve SEO on your main domain name and you will be able to get more visitors.
This is technique is not new and I suppose that will drive some profit for your main domain name for sure.