One technique I use is to put the name of the current page in the session. For example, if the user is at the "Main Menu" page, getting the attribute "currentPage" from the Session will return that
string. Then, before I forward to another JSP page, I can simply set that session variable to the name of the page that I'll be forwarding to. This way, I always know where to look to determine where the user is and I don't have to include hidden fields in all of my pages that don't really mean anything. After all, does your JSP really care what the servlet calls it?
I also find that it's usually good practice to store my screen names as constants in some class (possibly the servlet, but I usually make another class to put them in to keep it from getting cluttered) or in a propeties file.
I hope that helps,
Corey