I have a few friends going traveling australia, south america & asia, what good gift could i get them?

i'd spend 20 - 50 euro....any ideas much appreciated

Underwater camera (cheap point and click as it'll stay waterproof even through rainy seasons. Useful when snorkeling too obviously).

If they're backpacking and need to save weight, travel towels are a great and very useful gift. They're much lighter and more absorbent than a normal towel and much easier to wash and dry too. Get the largest you can afford.

I would recommend a travel journal then they can make notes of all the places they have seen x

A prepaid VISA card, a good quality windcheater will come in handy, a voucher for an activity i.e. Sydney Harbour Bridge Climb, a travel guide book or maps, a travel adapter (power converters) one for each country, airport transfers i.e. offer to take them to and pick them up from the airport, help around their home (collect mail, put bins out, water plants, etc).. It doesn't have to cost money.