I've noticed that posting sig links in forums that are not relevant to my site still improves in the SERPs. I haven't tried posting the sig links in relevant forums - just wondering if it would help more. Has anyone tested sig links in relevant forums compared to forums that are not relevant?
Whether the forum is relevant or not, what would matter is whether the link is dofolow or nofollow, as seen in the eyes of google. Nofollow forum sig links are discounted from being taken into account by google. But it is taken into account by Yahoo. So concentrate on getting as many forum sig links as you can, by using forum posting method. Humans visiting the forum may be interested in the sig links so you will likely get some referer traffic from them.
Yes, The dofollow links with the keywords in the anchor text, and the Page Rank of the forum are the things that would actually matter the most
Signature links are also important specially in forums... What I do is put my sig with link because this is also backlink and can drive UV to my site.
In my experience posting signature links in relevant forums does work better than posting in non-relevant ones. I did however still get traffic from the non-relevant posts. Biggest thing to remember is posting in forums that are "DoFollow" and have a high Page Rank. That way search engines will follow your links. Here is a list I recently compiled of "DoFollow" Forums that might help you out. Enjoy!
Both having the same effect in SERP. But while using niche related forums you can get some more traffic and they can be changed as clients.