RV is a great multi-purpose tool that begs to be integrated into nearly every part of our pipeline. For example, I've got a working prototype of an Arnold driver that streams to an RV instance. This is useful, but as people are already discovering with the Nuke integration, the fact that RV is an external application detracts from the user experience (https://support.shotgunsoftware.com/entries/96056017). What would be better would be if we could have an RV library that allowed us to load RV as a sub-window within Qt applications. Then the RV integration would be completely seamless: it would use the native windowing system (think expose in OSX), it could easily trigger callbacks within the host app (ex. in maya "select object under pixel"), and eventually, it could be directly passed tiles in memory instead of socket streaming.
Maya in particular is in desperate need of a new render viewer. It has not been updated since Maya's inception, and still does not support multiple AOVs, pixel value under cursor, interactive gamma/luts, float values, A/B comparison tools, meaningful hotkeys, and on and on. A library like this would open the door for a killer plugin for renderers to hook into, and would also improve Nuke integration as well.