KnightCite Citation Service: creates citations in MLA, APA and Chicago styles.
Citation Machine: creates citations in MLA, APA, Chicago, and Turabian styles.
Noodletools.com: a great site to create citations in MLA and APA styles.
The OWL at Purdue: Provides an online writing lab with complete guides to MLA and APA styles.
Easybib.com: online tool creating citiations in MLA, APA, and Chicago/Turabian styles