Does anyone knows of a cheap application to track multiple (say 50) mobile phone locations?

The phones will be either Nokia E72 or Nokia C5 (both have GPS and 3G) and Vodafone data connection.

I want all the phones to be tracked.

I know there are some fantastic commercial fleet management systems - which are pretty expensive.

But I want a cloud type application where you type in all the mobile phone IMEI codes into a web page and install the application on the phones - and you can just track all the users whereabout from a Web page.....

Thanks