stacksocial have a promo valid for USA Monday time/date (NZ yesterday 11-Dec) only so not sure of exact expiration in NZ time

use promo code "green40" at checkout.

I haven't purchased anything myself but it seems to work at checkout fine for Sid Meier's Civilization VI and VPN Unlimited: Lifetime Subscription. 
Both are each US$29 with the code bringing them down to US$18 each.

I'm sure there's other useful digital stuff available