hydrogen is totally free:
http://www.hydrogen-music.org/
Screenshots:
When it initially loads. on first run I had to resize the window to the minimum height it could be (alt f8, then some arrow key work to do so) and resized it to fill the screen width:
Now, everytime I run it I just hit alt f7 and press up 6 times to show the velocity/pan stuff. the only downside is that the menus are hidden....
This is the mixer window that automatically maximizes, and is accessable thru alt-tab or the first H2 logo on the top panel:
The other thing I did was download all the available drumkits (Instruments>import library). Had to do the alt f7 trick to access the download and install button, but still mighty nice and easy.