Save everything from online journal articles to records for books to plain old web pages. Then you can categorize them and export them as bibliographies formatted in any of the major citation styles.

EndNote's online version has the great advantage of being accessible from anywhere that has an internet connection and of allowing you to share folders with collaborators.
NOTE: You'll need to create your own login and password. Be sure to use your Carleton email address.

Mendeley, owned by Elsevier, lets you save and annotate PDFs. You can also search across your own and others people's collections.

Search, annotate, organize, and share PDFs.

Save entire web pages or just pieces of them, type in your own notes, search through everything, create categories, and have access from your computer, any computer, or your mobile device. Best option for saving notes and links and files in one place.

Save a web page (or image or video) now and read it later, whether you're online or not. Works well an all devices. Minimal organizational strengths - use for its offline abilities and lovely distraction-free reading.

Simple and fast bookmarking tool, allows you to save and organize links to the things you find online from any browser. Ad-free, tracker-free, but not free to you.

A bookmark manager with an optional app, Raindrop captures the URL and associated content (when possible) when you bookmark. Lovely email-like interface allows you to drag and drop organize into folders and read both a distraction-free or original version. Free for most features, but small fee includes nested collections, backup to Dropbox, and more storage.

Web-based bookmark tool for visual thinkers. Drag and drop your bookmarks to organize into categories, lists, and boards. Share and keep private what you choose. Good for arranging your readings into a workflow for read/unread or for how you will use resources in your research. Excellent interface but you see lots of ads.