Background processing in ASP.NET

As part of my bicycle climbs website, I need to spend some time calling a web service to fetch the elevation of 250 different points. Each call takes a few seconds.

Ideally, what I would have is a way to start the processing but not have it block my normal page processing operation.

Ideas? I looked at the MSDN docs here, but that requires me to continually refresh the page. I could do that if necessary if there's no other way.