BooksThere are a ton of great books out there. I've pulled together just a small handful of the ones that have been the most useful to me. You can take a look at my list on Amazon, read the reviews yourself, and see what you think.
ArticlesIf you only read one article, my advice is that this be it!
Clark, Ruth C., and David Taylor. 1994. The causes and cure of worker overload. Training 31, no. 7:40.
Other articles by Clark are available at her web site, Clark Training & Consulting.
Here's a couple more to check out:
Donovan, Carrie. 2004. Developing Web-Based Instruction. The Journal of Academic Librarianship 30, no.2:162.
Web SitesHere's a chance to plug Scott Walter's excellent site: Instructional Improvement in Academic Libraries
Also check out:
Rapid Instructional Design by one of the important contributors to the field.
Bloom's Taxonomy is very useful when writing learning objectives.
BlogsIDEAS: Instructional Design for Elearning Approaches