How much success have you had with this?

I mean posting on forums with links in your signatures. I've personally noticed a jump in my s.e. Position in Google with the keywords I'm using for my anchor text. However, it has begun to slow from me being on the 9th page to now being on the 3rd to not being able to really move up from there. I've used directory submissions but they take forever to actually look at your site and approve it for listing. I'm wanting to know how your luck has been when it comes to improving your SEO Through forum posting with link Signatures.