I hate threads like this for the reasons already posted.
If you want huge amounts of traffic build galleries that The Hun will list regularly and watch your server melt.
If you want a list of places to submit to
start with this list and watch your server stats for a few months to see which ones are working well with the type of stuff that you produce.
Many places are partner only these days so you may first need to build up a reputation to get accounts with them.