Purdue University Writing Lab
This excellent site includes information on documenting electronic sources (http://owl.english.purdue.edu/writers/documenting.html) as well as examples of MLA and APA style for print sources (http://owl.english.purdue.edu/files/33.html).

Colorado State Documentation Tutorials
http://www.colostate.edu/Depts/WritingCenter/
references/sources/document/page1.htm
Extensive discussion and tutorials on in-text documentation. An excellent resource.