http://www.bibme.org/

Whilst citing references is certainly a vital part of academic research, it is also very tedious. By helping to create and format references according to a given system (e.g. Harvard, APA, etc), BibMe makes this task a lot easier. Simply search for the item you need to cite and select it for addition to your reference list. If the system cannot find the item, just enter the details by hand, letting the system format it for you. Select your desired style and simply copy and paste into your document.

Whilst there are other systems that do more (such as integrating into your word processor), BibMe cannot be beaten in terms of balancing functionality with ease of use.