It seems that many people in DP are submitting their sites to free web directories (that are usually small). I'm interested in people's opinions as to whether these links really help a site or are they a waste of time?
Of course they help... Small websites appreciate the extra traffic they get from the backlinks and it all adds up.
It's free, it helps a little, thats why people do it. I don't think you'll ever get much traffic from directory links directly though. It's more related to SEO and increasing PR (which basically doesn't matter anymore).
It is free, and it may help with acquiring a new back link. However, if you are submitting to a low PR directory that doesn't properly categorize their links and will publish basically anything (link farm), Google doesn't like that. It can actually be somewhat detrimental to your SE rankings. But yes, submitting to a few certainly doesn't hurt.
My advice is backlink to as many related sites as you can, however if it means placing many links on a single page on your site, them make it look presentable.
Finebrains, I do believe mailing lists work, but they need to be targeted. Just a huge group of emails probably is not as beneficial as one might think when the people you are emailing are not interested in what you are offering.
I disagree, my friend... You need to take into account how many people simply empty their junk/bulk email folder and how many more people set their inboxes to receive new messages only from people they know, thus placing all other messages in the junk mail folders.