According to the write-up in Github:
Rogue is a type-safe internal Scala DSL for constructing and executing find and modify commands against MongoDB in the Lift web framework. It is fully expressive with respect to the basic options provided by MongoDB's native query language, but in a type-safe manner, building on the record types specified in your Lift models.
It sounds like this would be very useful for those using MongoDB with Lift. An admittedly small, but growing, number of developers.
The write-up for Fully-Loaded is shorter: "A highly opinionated image loader and cache optimized for UITableView scrolling performance."
It's become common practice for Web companies to release development tools as open source projects. For example, Facebook open-sourced Cassandara, Twitter open-sourced FlockDB and Yahoo has released Pig for Hadoop. Foursquare's tools may seem minor in comparison, but it's part of an ongoing trend.