SessionSaver Extension

SessionSaver is an extension for Firefox and the Mozilla Suite that will automatically keep track of your browser windows and tabs and restore them exactly as they were across browser sessions. Not even crashes can faze it: window positions, tab histories, cookies, scrolling and text in text boxes - all are saved. SessionSaver can also save individual sessions for future recall.

It has a host of options for experts to tweak, including session-storage (akin to Firefox's ability to bookmark all tabs in a folder), which allow a high degree of flexibility.