Hello,
I am addicted to social bookmarking sites now and stopped using web directories. There are several reasons I think social bookmarking sites are better than free web directories.
1. social bookmarking sites approve your web site, pages, immediately.
2. you can submit any inner page to social bookmarking sites.
3. web directories take time to approve but no guanrantee.
I think my web site, new pages get indexed on search engines faster when I submit them to social bookmarking sites.
Thanks for reading and I hope I contribute something.