In two years this is the only blog directory that sends me enough traffic to be worthy of a mention,
Adult Blog Finder but I can not say I've had any success on my other blogs subbing here.
If your building long standing blogs that you want to continually work, then I don't believe any blog directory to be worth submitting to.
The ones I submit to are because they are people I know from the boards and not because I have any expectation of a decent return.
On the otherhand if you can find the rare aggregator that you can submit your feeds to AND you do update multiple times a day you can pick up some additional traffic.