If you would like to improve this system then why not log the clicks on in a database. If you were to create a database called banners.mdb with a table tblAds which has 3 fields id (select the autonumber datatype), url, and the date. Then you could put this code in the redirect.asp page. It will log the hit before redirecting to the url associated with the banner.
<%
Option Explicit
response.buffer=true
'declare your variables
dim connection,recordset
dim SQL,sConnString,URLofBanner
'get the url associated with the banner
URLofBanner=request.querystring("url")
'declare SQL statement which will insert the url of
the banner and the date and time of hit
SQL="INSERT INTO tblAds(URL,theDate) VALUES ('" & URLofBanner
& "', Now())"
'define the connection string, specify database
'driver and the location of database
sConnString="DRIVER={Microsoft Access Driver(*.mdb)};" & _
"DBQ=" & Server.MapPath("banners.mdb") & ";"
'create an ADO connection and recordset object
Set connection = Server.CreateObject("ADODB.Connection")
Set recordset = Server.CreateObject("ADODB.Recordset")
'Open the connection to the database
connection.Open sConnString
'Open the recordset object, execute the SQL
recordset.Open SQL,connection
'close the objects and free up resources
Recordset.Close
Set Recordset = Nothing
Connection.Close
Set Connection = Nothing
'finally redirect to the banner's url
Response.Redirect URLofBanner
%>