http://revach.net/article.php?id=4342

Section: Parshas HaShavua   Category: Numbers & Letters
Parshas Yisro: Maharal MiPrague & Maskil L'Dovid - What Is In The Name Yisro
Rashi brings from the Medrash that Yisro had seven names (see Revach Lists for names and reasons).  "The reason," says Rashi, "that he was called Yisro was because another name he had, was Yeser and when He was Migayer and took on the Mitzvos they added a 'Vav' to his name."  Why a Vav?

The Maharal MiPrague in Gur Aryeh says that Yisro with a Vav has a gematria 616.  That includes the 613 mitzvos plus the three that a Ger must do to be Migayer, which includes Mila, Tvila, and bringing a Korban.  Mila is not double counted as he still has a mitzva to do Mila on his children.

The Maskil L'Dovid says that Yisro includes all his names.  Yeser was one name, plus the Vav means he had six other names.