Review for FireTray by Pseudomonas
Rated 3 out of 5 stars
It crashed my firefox, too!
Mozilla/5.0 (X11; U; Linux x86_64; de; rv:1.9.1.7) Gecko/20100106 Ubuntu/9.10 (karmic) Firefox/3.5.7
But it worked well with a portable version of firefox.
To create your own collections, you must have a Mozilla Add-ons account.