It’s not exactly travel-related — but for those of us who love to earn something for nothing, Amazon is currently running a promotion for free one-day shipping when you use an “eligible” Citi card and when you buy “eligible” products.
The details are on this page, but it boils down to this:
1) Buy an eligible product (see their page for info)
2) enter promo code CITIFS13 when checking out
3) select one-day shipping.