Having a web form allows those on the site to easily fill in information you may want from them. This webform can be delivered to your email, go into a database or be loaded into a CRM.
Offer ebooks or white papers for download but ask for contact information from the person prior to allowing download. The user gets the information they were looking for and you also get the details of a prospect.
Offer a way for someone to register for your newsletter in strategic locations on the website. While the website is a more passive way of marketing, an email newsletter is a great way to constantly reach out to people.
An offer to get a free estimate or consultation on your services may be just enough to convince someone to take the next step and contact you.
Offering some sort of additional incentive can also influence contact. Be sure the the coupon is enticing and has a clear deadline. Coupons are also a great way to track the success of a website.