node names

One option would be using a class/data group. You could create a relationship between the node's IP address and it's friendly name. What version are you using?

An example for 10.1 and later would be to use class search - value.

You'd define a string-type data group (named servernames below) where the field was 192.168.0.100 and value was webserver1. Then, you might use a rule like the following:

when HTTP_REQUEST {
    HTTP::header insert "server_name"  [class search - value servernames eq [LB::server addr]]
 }