Rapid access to a large variety of cells is one of the keys to productivity in Microstation. In general, I find that locating and placing cells is still too clunky (inefficient.) I think Cell Selector has the basic idea and could be an excellent tool, but it needs to be updated. I envision being able to populate a Cell Selector pallet via drag-n-drop from the cell library dialog.
Also, cell selector needs to be much more flexible. I envision expandable cell collections, better graphics (i.e.: illustration vs wire frame), varieties of button sizes, easy setup, loading and navigation. Selector files should be easy to associate with any project (via configuration) or no project (create a selector map on the fly.) I had previously used Reveille (MDL App) in the early 2000's where you could build an extensive hierarchy of cell selector-type files. This was a great application which no longer exists. Though it was tedious to setup, it definitely had the right idea in terms of building a hierarchal system.