I find this question interesting because i still see people within forums stuffing their signatures full of keyword rich links!
Now the problem that comes about with this is that if you have got several thousand posts within any given forum this can really throw out the balance of your anchor text and your link profile in particular.
Because what happens,let's just say for instance i am targeting SEO and if i've SEO within my signature links then chances are i am going to have hundreds and thousands of inbound links all using that same term.
Look up Matt Cutts,he touched on this subject sometime ago and said that forum links are of no value in terms of SEO.
It is simply not a case of adding some keyword rich anchor text within your signature links and all of a sudden you start climbing rankings and hit the first page of Google!
So the short answer is that NO,signature links are not going to help you in terms of SEO.having said that though signature links can be very useful if they are used correctly!!
Signature links have the ability to drive extremely targeted visitors and that is because you are engaging with real people.If you are contributing to the forum and are helping people by providing useful advice to them and if you are actually engaging and providing real value to users then chances are that people are going definitely take a look at your signature link and click through which will lead them to your website/blog.
And that is essentially what you want.Now of course if you are just dropping links,promoting yourself and your brand and not providing any real value your signature links regardless of what you do or who you are are not going to help you in any way.
Now i will share with you a quick tip what i do within forums and how i can accurately measure just how much traffic is coming through my signature links.
Firstly i use the Google URL builder.This allows you to create a trackable URL so within my signature link i am not just putting bla bla bla.com i actually add a snippet of text with an underlying trackable URL!
Now this all ties within the campaigns within Google analytics,since i add certain parameters to that trackable URL so i know if anyone clicks on my signature link and visit my website i can look In Google analytics and see exactly where they came from.
Conclusion So this is a much smarter way of using signature links as opposed to just dropping in keyword rich anchor text within your signatures in hope that it will give you a boost in Google ranks because that is simple not the case.
So that is it for this article,hope this helped you out!