Trulia did something very similar to Bills.com with their landing page. It starts with a simple form asking for "an address" (which sounds less creepy than "your address," although that's what they mean). Below this simple form field is a bright orange button that contrasts well with the hero image behind the form, and emphasizes that the estimate will be personalized to your home.
The messaging on the page reinforces the reason for their click, reducing or removing confusion and therefore increasing conversion rates. This improves overall user experience and reduces the bounce rate (individuals leaving the site without converting or navigating to another portion of the site) for the page. Good message matching can increase conversion by up to 50% in many cases.
Whimsical isn't usually the first word that comes to mind when you think of HR software, but Teambit's illustration-heavy landing page is exactly that. A simple, one-field form is accompanied by a delightful office full of animal characters -- all of whom are very pleased with Teambit, in case you were wondering. An animal cartoon appears beside each informational section of the landing page, keeping visitors scrolling down to learn more.
I'm not sure how the algorithm works (or if there's one at all), but while I was filling it out, I had some anxiety about not qualifying. Once I found out I did, I was excited to fill out the form, which I'm sure most people who are in debt and using this tool are. By making this offer seem more exclusive before the form appeared on the landing page, I'd bet that Bills.com increased conversions pretty significantly.