--- a/.hgignore
+++ b/.hgignore
@@ -1,6 +1,29 @@
+# .hgignore - List of filenames hg should ignore
+
+# Filenames that should be ignored wherever they appear
 ~$
+\.pyc$
+
+# User files that may appear at the root
+^\.mozconfig$
+^\.mozconfig\.mk$
+^\.mozconfig\.out$
+^configure$
+^config\.cache$
+^config\.log$
+
+# subtrees from other repositories
 ^nsprpub/
 ^dbm/
 ^security/nss/
 ^security/coreconf/
 ^security/dbm/
+
+# Build directories
+^obj-
+^objdir-
+
+# Build directories for js shell
+_DBG\.OBJ/
+_OPT\.OBJ/
+