There are lots of ways to user your website to recruit participants for remote research study. (If you’re already confused, see this post for an introduction to live recruiting.)
Another option is to embed a form somewhere on your website that users can fill out to opt-in to your study. Here are a few examples of form tools you can use: the first one uses the Forms functionality in Google Docs, and the second is a standard Wufoo form.
Google Docs form:
Wufoo forms are basically the same, loading its responses into an online table (login required). As with Google forms, you can link to page that contains only the form.