True virality is almost impossible to force and seldom accomplished by finding the easy road. Everything you've listed favors spreading but doesn't feel particularly unique to me [i.e. I can already use one of many services for polls] and I doubt you'll find the spark idea from asking others, although discussing the ones you have is a great approach.
But really I'd suggest you think less about how to "make something viral" and more about turning what you're already doing into an easy funnel that lends its self to being shared. If your business is about consumer insights a widget gaining customer data makes sense; if it's about humor that doesn't really fit the bill for bringing you useful growth or attention.