Other credit cards have them but CitiBank was the first I think. I just click "generate a card", tell it the amount, and there it is. A lot of on-line porn sites charge less on an "automatic renewal" and there are a lot of other promos for discounts with auto renewals. My XM is $30 for 6 months with auto renewal at $20/mo. I've had it for 6 for 30 for ten years with virtuals.
I pay all these with virtual cards and have never been hassled for renewal fees. Charge doesn't go through, they just cut you off. Works every time for the "low introductory price with auto renewal"s. Also I use virtuals for dodgy onliners like overseas pharmacies, etc.