Today is Shavuot, the Jewish holiday (on 6 Sivan) that commemorates God's gift of the Torah to the assembly of Israel at Mount Sinai. It is the conclusion of the Counting of the Omer which began at Passover, indicating the expectation of and desire for the Torah. Thus God's salvation of the people from Egypt is connected to God's covenant and mitzvot at Sinai. http://www.jewfaq.org/holidayc.htm
In Christianity, Pentecost is the festival commemorating the gift of the Holy Spirit upon Jesus' followers. That story is Acts 2:1-31. The word refers to the fifty-day period from Easter that cultivates in this day, "the birthday of the church." In England and elsewhere, the day is also called Whitsunday, referring to the white garments worn by the newly baptized. http://en.wikipedia.org/wiki/Pentecost In Orthodox Christianity, Pentecost falls on May 31 this year.
In the United Methodist Church, today is Aldersgate Day, honoring the day in 1738 when John Wesley experienced an inner confirmation of his salvation, as he listened to a reading from Luther at an Aldersgate Street religious meeting.