Will registering and submiting your URL to business directories give you creditable backlinks? I'm thinking on the basis of yell.com, thomsomlocal.com and other such directories. Also would backlinks from forum signatures help drive up your page rank?
backlinks from forums like digitalpoint will help improve your rank on search engine. You just need to post frequently and also post on forums that discuss topics related to your articles/website
What I would say about forum link building is it is helpful for both purposes link building and traffic, so you are going to get benefit from forums and there is no loss as well, if you use some quality forums.
I never use yell.com, thomsomlocal.com, but I usually optimize my business site by using backlinks through forum, edu., social bookmarking, wiki, and 2.0. Those work to increase page rank of my site.
Submitting to good business directories may result in good PR as it used to be in the past. Though directory submission is not as powerful a technique as it used to be.
Those strategies will work, but you'll want to do a lot more than that. These days you can't just rely on one or two strategies and expect to get ranked well. Diversity is very important.