Three of the most reliable stand-alone citation generators. Simply enter the data from your source and create a citation. These support only APA, MLA and Chicago formats. Always check the result against a current style guide!
BibMe is a free citation generator developed at Carnegie Mellon University that produces citations and bibliographies in APA, MLA, Chicago and Turabian styles. It has some features not found in other free citation generators, such as autofill and the ability to switch between citation styles.
Citation Machine is a free site that automatically produces MLA, APA, Turabian or Chicago style citations for a variety of sources (but not bibliographies). Users can copy and paste citations into Word. It was developed by David Warlick, an educator.
KnightCite is a free site that automatically produce MLA, APA, or Chicago style citations for 25 types of sources. From the Hekman Library at Calvin College.