This tool will allow you to decode base64 encoded content, such as the body of certain email messages (mostly spam), and most email attachments.
Base64 encoding is also used for a number of other purposes, mostly when data needs to be transmitted over a link or stored on a media that is not 8-bit clean.
Feel free to link directly to the base64 tool from your site if you wish.
Mail me if you want the source code so you can include it on your own site.
If you live in Cambridge and want an aerial fitted I can warmly recommend Newcam Aerials.