Another use of batter.

Using Dosa batter as a bleach.  This is a harmless yet effective bleach.  My friend (who gave me this tip) says that dosa-batter is most effective for bleaching feet; to ensure there is uniformity in color, especially for those who use sandals.
I like this use of batter because - it is usually available and harmful chemicals are not present.  After enjoying a batch of idlis/dosas, the last drops of batter can be put to this use! :)