R Yisroel Bronstein, writing in Halachos of Ma'aser Kesafim, answers your question (p. 123)
It is permitted to use maaser to buy a gift for a poor chasan, for
a bar mitzvah boy whose father is poor, or for a needy family in
honor of their son's bris. If one would anyway give such a gift from
non-maaser monies, then the use of maaser is forbidden.
As DanF already answered, there's a requirement to give gifts on Purim.
And as Joel K mentioned in a comment on the question, N'chemya 8:10–12 discusses gift-giving on Rosh Hashana (the date is in verse 2).
Rambam, Sh'visas Yom Tov 6:17–18:
The seven days of Pesach, the eight of the holiday [Sukos and Sh'mini Atzeres], and other holidays are ...