I"ve found that the quickest way to generate some rapid click and download volume are short videos and general industry white papers with a "5 tips for... " or "7 things to avoid..." If you're looking to generate a sizable amount of volume and have a budget, and maybe a little bit of time, partner with a industry analyst to sponsor a report.
There is a caveat with this though, these are good for seeing who the hand-raisers are, but these hand-raisers may not be fully ready to engage in a conversation about a free trial. But, at least they will be talking to leads who have at least expressed an interest in the general topic / industry / etc.
My humble suggestion would be to create a quick and dirty engagement program with a few easy to digest pieces like a blog post, followed up by accompanying short whitepaper, and then a free trial call to action or short video of how your product helps a specific pain point... and then use an engagement score in the program to quickly throw things over the wall into a "call ready" list.
Hope this helps.
Dave