Index: channels/bookmarks.py
==================================================================
--- channels/bookmarks.py
+++ channels/bookmarks.py
@@ -103,11 +103,11 @@
         row["favourite"] = 1
         if not row.get("favicon"):
             pass#   row["favicon"] = favicon.file(row.get("homepage"))
         if not row.get("listformat"):
             row["listformat"] = self.parent.channel().listformat
-        if not row.get("extra"):
+        if not len(row.get("extra", "")):
             row["extra"] = self.parent.channel().module
 
         # append to storage
         self.streams["favourite"].append(row)
         self.save()

ADDED   contrib/bookmarks_show_extra.py
Index: contrib/bookmarks_show_extra.py
==================================================================
--- contrib/bookmarks_show_extra.py
+++ contrib/bookmarks_show_extra.py
@@ -0,0 +1,43 @@
+# encoding: utf-8
+# api: streamtuner2
+# title: UI: bookmarks: show `extra` field
+# description: Extra field in bookmarks list
+# version: 0.0
+# type: feature
+# category: ui
+# config: -
+# priority: rare
+# 
+# Just injects the `extra` column for display
+#
+##
+# Now some of the workarounds (clean treeview) wouldn't be necessary if this
+# was loaded prior to bookmarks plugin. But alas we don't have #order: loading
+# support in ST2 init/pluginconf.
+#
+
+from config import *
+import copy
+
+# Inject into .bookmarks.datamap[]
+class bookmarks_show_extra (object):
+    plugin = "bookmarks_show_extra"
+    meta = plugin_meta()
+
+    def __init__(self, parent):
+        bm = parent.bookmarks
+        # clean treeview
+        for c in bm.gtk_list.get_columns():
+            bm.gtk_list.remove_column(c)
+            c.destroy()
+        # inject new column
+        bm.datamap = copy.deepcopy(bm.datamap)
+        bm.datamap.append(
+            ["Extra", 40, ["extra", str, "text", {}] ]
+        )
+        # redraw treeview
+        bm.columns([])
+           # @bug: does not update existing {text:IDX} attribute for columns,
+           # just happens to work for .append()
+  
+