This is a change I apply to most Redmine deployments but I never thought about posting it here before, until now.

Currently the issue link titles are roughly[1] rendered as "@issue.subject@ @(issue.status.name)@".
I propose to add the name of the tracker of the issue in front of the current text followed directly by a colon and a space.

|<. Now |<. Proposed |
| @issue.subject@ @(issue.status.name)@ | @issue.tracker.name:@ @issue.subject@ @(issue.status.name)@ |

This can be done by changing source:/trunk/app/helpers/application_helper.rb@11784#L697 like:

Index: app/helpers/application_helper.rb
===================================================================
--- app/helpers/application_helper.rb   (revision 11784)
+++ app/helpers/application_helper.rb   (working copy)
@@ -694,7 +694,7 @@
               anchor = comment_id ? "note-#{comment_id}" : nil
               link = link_to("##{oid}", {:only_path => only_path, :controller => 'issues', :action => 'show', :id => oid, :anchor => anchor},
                                         :class => issue.css_classes,
-                                        :title => "#{truncate(issue.subject, :length => 100)} (#{issue.status.name})")
+                                        :title => "#{issue.tracker.name}: #{truncate(issue.subject, :length => 100)} (#{issue.status.name})")
             end
           when 'document'
             if document = Document.visible.find_by_id(oid)

fn1. the subject is actually truncated at first