Asp 2.0 provide listbox control but one cannot seach in web application But the same is poosible in ajax
How To use:

In the Source code window type:

<form id="form1" runat="server">
<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</asp:ToolkitScriptManager>

Click on me to search an item
<asp:ListBox ID="ListBox1" runat="server">
<asp:ListItem>India</asp:ListItem>
<asp:ListItem>Pakistan</asp:ListItem>
<asp:ListItem>Afganistan</asp:ListItem>
<asp:ListItem>america</asp:ListItem>
<asp:ListItem>south Africa</asp:ListItem>
<asp:ListItem>London</asp:ListItem>
<asp:ListItem>USA</asp:ListItem>
<asp:ListItem>China</asp:ListItem>
<asp:ListItem>Canada</asp:ListItem>
<asp:ListItem>Washington</asp:ListItem>
</asp:ListBox>
<asp:ListSearchExtender ID="ListBox1_ListSearchExtender" runat="server"
Enabled="True" PromptPosition="Top" PromptText="Click on Listbox to search"
TargetControlID="ListBox1">
</asp:ListSearchExtender>

</form>


Here is the Code and its works .

what u need is just take a asp listbox control
Add an listbox extender with it u can specify the promptef text for the listbox searching

Note:The Code also work for dropDown Searching