Rated 5 out of 5 stars
Firefox's built in "When Firefox starts.. load my windows and tabs from last time" option is rather lame, as it assumes users will *always* want to start up with the same behaviour.
A Firefox developer posting on Mozillazine once told me that (an option) to have per-session chance to restore tabs and/or windows would be "an incredibly annoying, invasive, stupid design decision" and that as such they "most definitely" would NOT be implementing such a thing.
Looking at the # of downloads of this extension (currently 1,297,440), I'd say a heck of a lot of people disagree.
Session Manager has always been great to have, but since v0.6.3 it's now even better as you can choose which tabs to open, or not open (which is great if one tab is crashing the browsing). Thanks!