If you do a lot of online research and you use Firefox, and you haven't already installed Zotero, you should. It's probably the single most useful Firefox extension for research I've found, and possibly the most useful research tool I've found, period. It's a powerful but easy tool for saving research from the web or online databases in an organized way.
Zotero is especially valuable for legal research because if you're using a subscription database like Westlaw or LexisNexis, and you're charged per transaction, you can use the database to access a source once, save it with Zotero, and come back to it any time without having to use Westlaw or Lexis to retrieve it (of course, be careful not to run afoul of copyrights).
Zotero lets you keep an ever-growing, searchable, organized, portable private database, with your various research "collections" organized in a drill-down table of contents; within each collection, you can create sub-collections, which means you can also use Zotero as a kind of mind-mapping tool, starting a new sub-collection for each sub-issue in your research problem.
The interface stays visible and editable while you navigate through pages in Firefox, too, which is an overlooked feature in a research tool: being able to use both a research tool and a browser window without having to toggle back and forth between them saves time (I envy those of you with a two-monitor set-up).
The only reservation I've had about Zotero has been some bugginess. Now Zotero has just released a new version, and it looks like it could be a leap forward, with a lot of bugs fixed and some new features as well. I just installed it in my Firefox, so I don't know for sure yet just how improved it is, but this is the most excited I've been to get an update to a Firefox extension.
If that's not a nerdy statement, I don't know what is. Oh well. I kind of gave up on being cool when I enrolled in law school. Enjoy.