A "big" one that isn't included on your very helpful list is Survey Gizmo ( www.surveygizmo.com). They have several different levels of features (of course you pay more for more). APA uses them for their survey work; from what I understand, that is in part because of their security features.

 

One irritation that I've encountered with it is that if someone has opted out of another survey, it opts them out of all SG surveys. So, you have to get them to opt back in to yours... Otherwise though, it's a very flexible tool.

 

(From : Andrea Solarz)