Hi, does anyone know of a website that you can check to see if the Blackberry network is down?

I don't think there is any such web site. There are way too many pieces to the puzzle - is it RIM, is it the carrier, is it a particular cell or region for the carrier. The closest think I know of is a list server at Welcome to Rimoutages.com

Wirelessly posted (8700c: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0) BlackBerry8300/4.2.2 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102)

If you have t3 support or higher from rim you can get emailed about outages. But obviously that comes at a cost

That's the reason for the mail list. No cost to anyone that joins it and 98% of the time, the same info you would get from RIM comes through the list anyhow.