It's no surprise Unbounce is near the top of this list -- they've actually written the book on creating high-converting landing pages. Although there are lots of amazing things about this landing page, the two that I absolutely love are: 1) The use of a chat window instead of a classic form, and 2) the detailed -- but well packaged -- information below the form.
If a sales opportunity does not move down the funnel, the sale will not happen and the opportunity should be removed, hence the “leaky” funnel. A leaky funnel is not necessarily bad; as a salesperson, you want to focus on opportunities that are likely to yield results. It is the nature of sales to have to remove an opportunity from your funnel. It does not mean that you will not sell to that account (a positive action by the customer can put them back into the funnel), but for the time being, you should centre your attention on opportunities that remain in the funnel.
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.
Webflow, a design tool for web developers, packs a lot of information into just a GIF and three form fields. Having the entire sign-up form on a single line is a nice touch here -- not only does it make the page shorter, but filling out each box from left to right shows users how close they are to clicking the fourth blue button and getting started for free.