Just as the title says. I'm going directory submitting and I want to know how many sites until it makes a point difference. I know it won't add a point right away, but in the future. Like.. how many PR 5 sites do I need... how many PR 9 sites.. etc. Thanks.
Directory submissions mostly don't pass a lot of PR or SEO importance (unless it's dmoz, yahoo directory etc). the amount of pr a site passes on to you depends on the number of outgoing links in the page containing your link (and of course the PR of the particular page)
Completely impossible to say - and not that simple. (As Ana says - it depends on how many other backlinks they are spreading their PR across. ) The other thing is that 'points' aren't all equivilant. For eg it is easier to get from a PR1-PR 2 than it is to get from a PR2-PR3 etc etc. Just get link building and be patient...