Have recently been ramping up my list of traffic resources, & came across this little beauty. It's a great time-saver instead of typing different search strings in to Google.
Here's the link - some kind person has put together
The Ultimate List of Blogs that Accept Guest Posts
It also shows you pagerank, mozrank & alexa rank. Do your own due diligence on the viability of the numbers.
The references seem to be a mix of both free & paid posting opportunities.
Some people bag guest blogging/posting, but it still works well enough as far as I'm concerned.
Hope you get something out of it