I just setup my first SPF record (finally).
These sites were useful:
A great wizard to create the string(s):
http://www.openspf.org/index.html
http://old.openspf.org/
A good site for testing your SPF rules as they apply to various IP addresses:
http://www.seoconsultants.com/tools/spf/
AOL has a lot of information about these things:
http://postmaster.aol.com/spf/
Good thread on current state of SPF, DKIM, and who uses it: http://ask.slashdot.org/story/14/11/02/1741211/ask-slashdot-how-useful-are-dmarc-and-dkim
Tags: anti-spam, dns, prevent, reduce, joe job, domain name system, back-scatter, spf