It's nearly impossible to provide an accurate quote to a prospective web design client without first gathering information about what that particular client needs. Some designers do this in either a face-to-face meeting or over the phone, but more often, they have a questionnaire that prospective clients fill out. This is preferable for a couple of reasons, but the most important is probably that this document then becomes an integral part of the design process and is available to refer back to along the way.
So the question is whether you should put that questionnaire up on your website, or only send it to prospective clients once they've contacted you. There are a couple of reasons you may want to make it available online, but the obvious one is that clients are often eager to get started with their projects and so by providing the questionnaire online, this eliminates a step in the pre-contract part of the process.
Here, we've collected questionnaires and worksheets used by actual web design companies, including some of the leaders in the industry. There are both online and downloadable forms included, as well as the pros and cons for each format.