Do you know about these Firefox extensions?

My browser of choice is Firefox, and to make Firefox even more efficient, I've plugged in a few Firefox extensions that do specific tasks. Here are the five Firefox extensions that I use every day:

• Foxmarks is a free add-on for your Firefox browser that syncs your bookmarks across multiple computers. Basically, this means that my bookmarks can be accessed from anywhere, and they're backed up every time I shut down my computer.
• AideRSS Google Reader Extension: I use  Google Reader to keep track of all my RSS feeds. The AideRSS Google Reader Firefox extension helps me find the best content within my feeds instantly via a simple scoring system.
• Diigo Web Highlighter and Sticky Notes: I use this one all the time to leave sticky notes to myself on Web pages, whether that be an idea I want to follow up on, research, or just commentary.
• Session Manager has saved my bacon quite a few times. It saves and restores the state of all open windows - either when you choose to restore them, or automatically at start up and after crashes (which unfortunately, happens to me quite a bit).
• Download Statusbar: This extension is quite simple; it displays your downloads in a tidy status bar at the bottom of your browser, rather than a large pop-up window right in the middle of what you're doing.

See how useful these are? What are your favorite Firefox extensions?