A solid roller! The floating window and dock menu are fantastic additions. Perhaps the Dock roller could also give out a Growl alert?
Also, if an option could be given for the window to either show the animated dice, or just smaller buttons with "d4, d6" etc? It would be an even smaller footprint and less visually distracting, at the compromise of the dice being less visually identifiable (hence why only as an option).
This is a good product, and I'll use it as my roller during sessions from now on. If it could roll pools of dice with options like "drop lowest/highest" or you could enter formulas on the fly instead of just presets, I'd happily replace my other dice roller app with this; it certainly already looks better!