Beware of bug in version 0.6.7.4 Rated 5 out of 5 stars
When re-loading a session, version 0.6.7.4 of Session Manager does not allow me to choose which windows and tabs will be re-loaded. Sometimes double-clicking will toggle the check marks, most of the time it won't.
New users should be made aware of this. That's the reason for submitting the problem as a review.
This would normally be submitted as a bug report, but submitting a bug report requires that your email address be made public! Making an email address public causes a huge amount of spam. I suppose that Mozilla Foundation's way of discouraging bug reports.
Otherwise, I have found Session Manager to be excellent. It is absolutely necessary because Firefox is unstable and crashes often if you open many windows and tabs and put your computer into hibernation or standby.