We visited India 2 years ago with DCs 12,11 and 9 and are going again this summer. Last time I took bubbles (which were fiddly to show them how to use) to give to children and we also gave away clothes, sweets etc. I'm trying to think of things that are easy to carry and useful or fun.
Silly Bands Notebooks Pens
Any other ideas, experiences- we'll be travelling around a lot on trains but luggage isn't really a problem ( I drew the line at footballs as suggested by DD2)