I’m not Indian or Mexican, but they’d probably love a polish gift! Make sure it’s the right price point, but a super traditional polish wedding gift, especially if you can write a note explaining it, would probably be a lovely gift. Extra points if it involves some tradition or a marital check in at a year or six months or something.

I'm not Indian, but I've got a few Indian friends and have attended a few Indian weddings as well. From what I've seen, there's no "traditional" gift - most of the gifts I've seen are something which would be useful for the couple or their house, eg a dinner set, clothes, jewelery, maybe even a gadget or appliance. But this really depends on the couple - younger couples these days may explicitly say no to any physical gifts (because they may just end up becoming clutter) and would prefer accepting cash or gift cards instead. So if you're close to your friend, I'd say ask them upfront what sort of gift they would prefer or if there's any type of gift they wouldn't want - and that should help you narrow it down. Beware that they may say not to worry about bringing a gift and just your presence alone would be a gift (I've heard this dialog a few times...), but regardless, you shouldn't back down, and insist that you will gift them something irrespective of what they say, so this should make them back down if they're being stubborn. :)

As someone else said, a Polish gift might be a good idea - doesn't have to be a "useful" thing, but something symbolic to remember you would be nice.

so... a blender is probably off the table?

I'd suggest just straight up asking. if they insist on nothing- and you still want to, something small and fun. maybe a gag gift that'll make everyone laugh, or just something that's 'you'.

American here, but I agree with a traditionally Polish or German gift. I’ve always thought Polish pottery is lovely.

I went to a Sikh wedding a while ago, the groom's family was Sikh and the bride's family was from Vancouver. After the service the bride and groom sat on the floor while people talked to them from behind. As they were turned to talk to the people behind them everyone else would pass in front of them and leave money in their laps. There were no gifts.

They also did a North American type reception a few days later and there were gifts for that but they were registered.

Does the couple have a gift registry?

You reminded me about my neighbour wedding. She get together with Scottish guy and tradition was that theyr fathers have to wear national dress of the other one.

So my neighbour had a kilt and the Scott had something like this:

http://www.kyjovskekroje.cz/pujcovna/ukazky.html

Mexican here. Gifts are a must in mexican weddings, but I know nothing about Indian culture. As the actual wedding taking place in India, one must assume it'll be tied to Indian weddings protocol, so I would suggest you ask your friend about this.

Money for indians. Im in the UK and depending on how close you are you we typically give anywhere from £20 upwards. Theres a tradition of giving an extra£1 though so it would actually be £21, £31, £51 ect.

Mexican gifts are usually money. They'll even have a dance where guests pin money on the bride and groom while they dance.

An Ikea gift card is the traditional wedding gift of modern times.