Alas, poor Rando, we knew it well. Actually, not that well - that was kind of the point. This photo sharing app from the developer of Whale Trail eschewed the usual reputation and tagging systems of most photo sharing services in favor of a one-at-a-time approach. But after a Russian programmer created a script to game the system and upload thousands of identical photos, thus funneling all of Rando's unique content to himself, the developers shut down the app and the service. You can read more about it in this extensive TechCrunch interview.
The idea behind Rando was refreshing, if a little anti-social: you take a photo, then share it to the service. The photo is sent to exactly one randomly-selected person, somewhere in the world, with no message or context attached. For your trouble, you then receive a photo from a different randomly-selected user. It's an interesting idea that gleefully abandons the pretense and self-satisfaction inherent to services like Instagram and Pinterest. Unfortunately Rando solves a problem that doesn't exist, and as cool as the idea is, developer ustwo couldn't find any way to effectively monetize it. Rando had a year of uptime and nearly a million downloads, somewhere between 100,000 and 500,000 on Android.
A Russian programmer created a script that flooded Rando with identical photos, "hogging" all the new snapshots for a single user.
The last straw for Rando came from a 20-year-old Russian programmer, who devised a way to automate the upload process and bypass Rando's admittedly feeble software protections. His script uploaded 50,000 identical photos from his account, thus ensuring that basically all of the new photos uploaded to the service would be sent to him and only him. Ustwo banned the user, but the script was already released online, and other users were giving it a try. Stopping this kind of attack would require "extensive" development for Rando's apps and servers, and apparently ustwo couldn't justify the expense and the time for a service that was more of a curiosity than an active part of the business. They removed Rando from the Play Store, the iTunes App Store, and the Windows Phone store.
Rando creator Kenny Lövrin says that ustwo would be happy to pass Rando on to someone who could make it more financially viable, but for the time being, the interesting photo sharing experiment is over. If you're feeling the loss, maybe you can track down an old Polaroid and start leaving snapshots on random bulletin boards.