Articles about Fundraising from Mal Warwick & Associates - a goldmine of information and guidance. Also on this site, check out the list of ten most important reasons why people respond to fundraising letters.
Groundspring.Org, formerly eGrants.org
You will be amazed by the number and types of resources here. Although the site seems oriented to fundraising via the Web (including a "Donate Now" link), it is rich in all kinds of resources and information. You will find a link for downloading a free .pdf version of their "Online Fundraising Handbook" by clicking on "Learning Center."