By the post office or the bus depot. Today, I saw the nest by the railroad tracks behind some business (can't think of the name of it) but I think it was down Blackhawk Drive. They posted sitings on ebird last year but not too many postings this year. Also, there is a page on facebook called Beloit Bald Eagles ...
http://www.facebook.com/#!/BeloitWIBaldEagles
This is a shot I took last year out there. It was taken by the river near the bus depot. If you click on the photo, it will take you to my flickr where there are a few others that I took that day. It was below zero out that day ...alot different than today!
BE by Denise Trocio, on Flickr