Just started to pick up jquery recently and was playing with calling a .net web service from my page. Was really easy once I used Firefox Firebug to do my debugging and figure out some of the variable names to use to access my data.

Here is my final code

Javascript in page

<script type="text/javascript">
    $(document).ready(function () {
        $.ajax({
            type: "POST",
            url: "default.asmx/GetCatalog",
            cache: false,
            contentType: "application/json; charset=utf-8",
            data: "{}",
            dataType: "json",
            success: handleSuccess,
            error: handleError
        });
    });

    function handleSuccess(data, status) {
        for (var count in data.d) {
            $('#bookTitles').html(
                ' <strong>Book:</strong> ' + data.d[count].BookName +
                '    <strong>Author:</strong> ' + data.d[count].Author +
                ' <br />'
            );
        }
    }

    function handleError(xmlRequest) {
        alert(xmlRequest.status + ' \n\r ' +
            xmlRequest.statusText + '\n\r' +
            xmlRequest.responseText);
    }
</script>

and the div that I write the content to

<body>
    <b>Books List</b>
    <div id="bookTitles"></div>
</body>

and my Web Service and Class Catalog

[WebMethod]
public Catalog[] GetCatalog()
{
    Catalog[] catalog = new Catalog[1];
    Catalog cat = new Catalog();
    cat.Author = "Jim";
    cat.BookName = "His Book";
    catalog.SetValue(cat, 0);
    return catalog;
}

public class Catalog
{
    public string Author;
    public string BookName;
}