Zotero is awesome, and I'd also recommend the browser extension with an account. Account is free, but it'll let you save any web sources with all the metadata you need and sync it to the main program.

Zotero in combination with LaTeX and Biber have saved me so much time. Especially when I had a crazy professor who would make last minute changes to style requirements. I remember we had a paper to write that they initially said "Just cite with whatever format you want, it's fine as long as they info is there." Cool, write my ten pages or whatever with footnotes containing short citations and full citations available in the bibliography at the end. The night before the paper was due, "Actually, I need all papers to use APA citations or you'll be docked points.". No problem, just change my citation style at the top of my LaTeX doc and tell it to reprocess the paper, all the citations fixed in about 5 seconds, without even needing to learn the ins and outs of APA formatting.