Valve has introduced Steam Gift Cards, so you can send Steam Wallet currency to a friend.
You'll need to be friends with the recipient on Steam, and have had them on your friends list for at least three days.
You can't send existing Steam Wallet funds, however.
Here in the UK, Steam Wallet Gift Cards are for sale in £4, £10, £25, £50 and £100 variants. Buy one for a friend in another region and it'll get converted to your pal's local currency.
You can, of course, still gift specific games to friends - this is just another option. Hopefully they don't spend all your gift money on loot boxes.