I don't use the Arp very often, but every time I do, I come away a bit frustrated.  It seems like a great resource, but navigating through those pattern selection trees is murder.  When I do find something interesting, it's very hard to mentally file it away.  (Was it Keyboard Riff 32? Or Lead Riff 23?)
 
How hard would it be to add functionality for navigation and preview to the Arp files? Perhaps even add an arp pattern category to the existing browser.  I'd love to be able to check out the patterns with a predefined synth (like I can in the browser with MIDI patterns) and a specific input pattern or at least key.  How would that riff sound through a harp-like synth in F#m?
 
As I said, I don't often use the Arp, but when I do I don't usually love the experience.  What do you think?