Carlos de Grails

This is already handled by Firefox’s very own Multi-Account Containers extension.

I like to add Sticky Window Containers for extra functionality. Sidebery also works well with containers.

Apart from the ones already mentioned,

• being able to collapse all threads in a post to only show parent-level comments
• keyboard shortcuts ala RES (esp the J-K navigation)
• more themes (the default ones suck)
• more image improvements