Been working on the post-production phase in a web project recently, and some features can be really nice to have..

1. Prevent duplication form post when you insert a new record.
http://www.eggheadcafe.com/PrintSearchContent.asp?LINKID=98

<SCRIPT language=JavaScript > 
                    var submitcount=0;   
                   function checkSubmit()
                   {     
                    if (submitcount == 0)
                       { submitcount++; return true; }  
                    else
                       { alert('This form has already been submitted.' ); return false; } 
                    } 
</SCRIPT>

<form name=frmSubmit method=post onSubmit=" return checkSubmit();" action="mypage.asp" >

2. A simple progress bar to wait the next page...
http://blogs.crsw.com/mark/articles/642.aspx
http://blogs.crsw.com/mark/samples/BusyBoxDemo/Default.aspx

 All that is need for this page is:
- a single line of code to reference the busy box javascript.
- a small javascript statement in the body tag's onbeforeunload event.
- a small iframe tag.
- a single line of code to instantiate our busy box object.
- a BusyBox.htm file to reference (or any name you like).

3. Open IIS6 compression to make asp.net faster
you need to manually modify the iis6 config file, just following through the links
http://www.dotnetdevs.com/articles/IIS6compression.aspx
http://support.microsoft.com/?id=322603

4. Make the block collapsable
example is in a custom control format

//this is the javascript function to be emitted.
  private string getJsScript()
  {
   StringBuilder sb = new StringBuilder();
   sb.Append("<script>\n");
   sb.Append("function collapse(id){\n");
   sb.Append("var ul = document.getElementById(id);\n");
   sb.Append("ul.style.display = (ul.style.display == \"block\") ? \"none\" : \"block\";\n");
   sb.Append("}\n");
   sb.Append("</script>");

   return sb.ToString();
  }

//release the javascrip
  protected override void OnPreRender(EventArgs e)
  {
   Page.RegisterClientScriptBlock("collapseScript", getJsScript());
   base.OnPreRender(e);
  }

//in the create control function add the javascript function call when click
  protected override void Render(HtmlTextWriter writer)
  {   
     this.EnsureChildControls();
     string ulId = "leftmenusep";

     writer.AddAttribute("src", CollapseIconLocation);
     writer.AddAttribute("onclick", String.Format("javascript:collapse('{0}');", ulId));
     writer.RenderBeginTag("img");
     writer.RenderEndTag();
}