Great program! Just a couple of suggestions:
1) Maybe I'm missing this feature, but it seems that when you select a few files in Explorer (Vista), and choose "Bulk Rename here", BRU ought to have those same files selected in the main window. Instead, I have to select them AGAIN in the BRU window. (help?)
See Creative Elements Powertools' renamer as an example.
2) It might be nice to put a mild color coating on the different sections at the bottom. When they are all grey, you really have to hunt. But colors help your eye to separate and organize more effectively.
See 1-4a Rename (Superb Batch Renamer) as an example.
I think if you incorporate the strengths of those utilities, BRU would be the absolute best!