incrediBILL - 6:02 am on Mar 18, 2008 (gmt 0)

I actually block all automated submission tools simply because most of them are used to submit off topic junk to my niche site and for many of the reasons Webwork mentioned.

I also block anything coming from Google using a query "add url" or "submit url" or other keywords that typically result in junk.

Submit to the directories manually because you might find out that many of those directories aren't places you would even want your site associated with if you spent 5 seconds to look around.