Sig Links - Are they really worth it?

[bigcat1967]

First of all - here is where I think you can get quality links:

1) From relevant sites (great if it has high PR)

2) Article Submissions (EzineArticles would be the best)

3) A few doFollow SBM sites (high PR again)

4) Maybe a few directories (better if they are niche directories)

I think sig links don't add that much value - any comments?