Are there any customs from modern or historic communities involving the celebration of a person's conversion to Judaism? In contrast to other transformative occasions in one's life (i.e., bar mitzvah, marriage), I can't think of any custom or ritual relating to celebrating this event, with the exception perhaps of a man receiving his first aliyah on the following shabbat. There are scores of piyutim (liturgical songs) that have been written for circumcision and bar mitzvah events, and both traditionally include other rituals (brit yitzkhak, seudat mitzvah, etc.)
I am familiar with couples who marry "again" once they both complete conversion, but I'm curious to know if there are standard forms of celebration for a new convert.