Excellent JQuery FAQ and live explanations

http://jquerybyexample.blogspot.com/2011/08/mostly-asked-jquery-interview-questions.html 

ModalPopupExtender .. a good one using

ref:http://www.codeproject.com/KB/ajax/ASPModalInAction.aspx

CollapsiblePanelExtender tips

1.Having multiple close\open buttons

   ref: a) http://stackoverflow.com/questions/744184/how-do-i-have-multiple-close-buttons-with-a-collapsiblepanelextender

b)http://stackoverflow.com/questions/6729999/asp-net-collapsiblepanelextender-two-expand-collapse-button-on-one-target

Sys.WebForms.PageRequestManagerParserErrorException - what it is and how to avoid it

Excellent reference

1) http://weblogs.asp.net/leftslipper/archive/2007/02/26/sys-webforms-pagerequestmanagerparsererrorexception-what-it-is-and-how-to-avoid-it.aspx

Modal UpdateProgress for UpdatePanel

ref1: http://mattberseth.com/blog/2007/07/modalpopup_as_an_ajax_progress.html - simple and easy

ref1: http://blogs.visoftinc.com/2008/03/13/Modal-UpdateProgress-for-UpdatePanel-Revisited/ 

ref2:  http://weblogs.asp.net/guillermo/archive/2008/02/24/ajax-how-to-create-a-quot-processing-quot-modal-window-using-updateprogress-and-modalpopup-asp-net-ajax-controls.aspx

Getting Ajax autocompleteextender selected value

1) create data source as  List<string>();

 List<string> custList = new List<string>();
            string custItem = string.Empty;
            while (dr.Read())
            {
                custItem=AutoCompleteExtender.CreateAutoCompleteItem(dr[0].ToString(),dr[1].ToString());
                custList.Add(custItem);

            }

2)In the Asp.net page

 <script type="text/javascript">
    function ace1_itemSelected(sender, e)
    {
        var hdCustID = $get('<%= hdEmpID.ClientID %>');
        hdCustID.value = e.get_value();
    }
    </script>
 <asp:TextBox ID="txtEmpName" AutoPostBack="true" AutoComplete="off" runat="server"
                    OnTextChanged="txtEmpName_TextChanged" />
                <cc1:AutoCompleteExtender ID="ace1" TargetControlID="txtEmpName" ServiceMethod="GetSuggestions"
                    MinimumPrefixLength="1" OnClientItemSelected="ace1_itemSelected" FirstRowSelected="true"
                    runat="server" />
                <asp:HiddenField ID="hdEmpID" runat="server" />

3) the the code behind 

   String selectedEmpID =  hdEmpID.Value;

Thats it! 

Ref: http://forums.asp.net/t/1608031.aspx/1?AutoCompleteExtender+Selected+Value+Feature