As I've mentioned previously I've been trying out different article directories. One of those that stands out is Sooperarticles.
It does sometimes take a few days or more to get your articles approved, but it's definitely worth the wait. Not only does it get a lot of traffic and have decent page rank, but your articles are indexed by Google very quickly. I just got an e-mail notification that my latest article had been accepted so I Googled the title and it was there.
It's much better that you wait a while to get an article accepted by a directory than wait for ever for it to get indexed.