I received the following request (quoted at the bottom) and thought it sounded too good to be possibly true. I get a good vibe, but I need you guys to look it over. Are there any negative implications that I should be aware of? Thanks.
These types of requests are sent out in mass - I've gotten hundreds. It's a way of obtaining a link for their site. Instead of buying/paying for a link from your site, they write an article with their own link pointing to their site.
So-called "Guest posts" are a very common practice. as mjewel pointed out, in exchange for a content contribution, guests are allowed to describe their business in a brief signature. You may give it a try if you're interested in materials from guest authors, however, first of all, check credibility of their resource, provide strict requirements for an article and settle an exact subject.
If the info is of benefit to your visitors - take it. Tell the requestor that you want a unique article that they are not sending to loads of sites ... then they deserve a link in my opinion.