Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
You can use Zotero on Mac, Windows, and Linux; you can also quickly create bibliographies online with ZoteroBib.
Zotero lets you organize your sources into folders, add tags for quick access later, and attach the full-text of the resource to the record. Additionally, Zotero offers plug-ins for Microsoft Word (Windows & Mac) and Google Docs for quickly inserting your in-text citations and creating your Works Cited/Reference List/Bibliography.
Zotero supports thousands of styles, including APA, MLA, and Chicago/Turabian. You can easily add styles to your downloaded app, and you can always tweak your citations/bibliographies to adhere to any professor or department requirements.
Bible & Theology students, don't forget to check with the BibTheo Turabian guide for how to tweak your Turabian citations.
Many library databases (like APA PsycAarticles or ATLA Religion Database with ATLASerials) let you export the citation and full-text of the article (when available) directly into Zotero. Additionally, the Chrome extension allows you to easily save resources from around the web directly to Zotero.