I like makepeacetotalpackage.com of Clayton Makepeace. Some of the guest posts are better than others, but there is a ton of good information there for free in the archives. There is at least one good thought provoking post a week. His products are good too.

Not to forget thegaryhalbertletter.com - which I am sure all of you know already.

And one of the last living legends of copy : draytonbird.com has some free resources and a hilarious bog, but you really need to own his book: Commonsense Direct MArketing.

Add Triggers of Joe Sugarman to that book list ...

The infomarketingblog.com of Lawrence Bernstein is very good too and has a lot of gems in the archives.

Conrad