Index: app/models/query.rb
===================================================================
--- app/models/query.rb	(revision 90)
+++ app/models/query.rb	Wed Jul 07 11:40:28 MSD 2010
@@ -184,6 +184,7 @@
     
     user_values = []
     user_values << ["<< #{l(:label_me)} >>", "me"] if User.current.logged?
+    user_values << ["<< #{l(:label_nobody)} >>", "nobody"]
     if project
       user_values += project.users.sort.collect{|s| [s.name, s.id.to_s] }
     else
@@ -430,6 +431,9 @@
         # regular field
         db_table = Issue.table_name
         db_field = field
+        if field == 'assigned_to_id' && operator == "=" && v.delete('nobody')
+	        operator = v.empty? ? "!*" : "=nobody" 
+				end
         sql << '(' + sql_for_field(field, operator, v, db_table, db_field) + ')'
       end
       filters_clauses << sql
@@ -508,8 +512,9 @@
   def sql_for_field(field, operator, value, db_table, db_field, is_custom_filter=false)
     sql = ''
     case operator
-    when "="
+    when "=", "=nobody"
       sql = "#{db_table}.#{db_field} IN (" + value.collect{|val| "'#{connection.quote_string(val)}'"}.join(",") + ")"
+	    sql = "(#{db_table}.#{db_field} IS NULL OR " + sql + ")" if operator == "=nobody"
     when "!"
       sql = "(#{db_table}.#{db_field} IS NULL OR #{db_table}.#{db_field} NOT IN (" + value.collect{|val| "'#{connection.quote_string(val)}'"}.join(",") + "))"
     when "!*"