You can say, Rakhi is the festivals of Hindu. In its background there is a great history but our purpose is not here to discuss that. On that day we know all the sister bind a Rakhi to her bother and expect some gifts.
In the age of modernization there are trend of electronic Rakhi. But we know still most of people celebrate it naturally. So, we can't imagine to send a electronic gift also.
Gift on Rakhi can be many things but most famous is money, Sari, Sweets, and gift with related age group. Decisions of gift we would have to take now because after some months there are festival of Rakhi.