Hay if I could install zappers in my hand and something to shoot fire out of my mouth I'd do that too, it would make getting served in a shopping centre much easier .
Seriously though, I haven't seen too many crazy addons for NvdA, its not like Winamp where you could get an addon to play packman in your Winamp window . Most of the ones I've seen usually have a little more point to them like providing program compatibility, extra functions to NvdA or tweaking some of NvdA's behaviours, rather than trying to emulate specific functions of other programs.
The only exception I can think of where an NvdA addon provides something that doesn't have a basis in NvdA itself, is the instant translate addon, and even that is more a matter of building a rather unique way for nvdA to interact with Google translate as opposed to creating a new function from thin air.
Also in the case of music players, to be brutally honest I'm not really sure why someone would want to use their screen reader to play music anyway?
I can't speak for the Jaws media addon, but the supernova entertainment function won't let you set supernova as the default media player for given file types. You can open the control pannel and play stuff, but not play things from windows explorer.
Similarly, the podcatcher works rather like that on the Victor stream with providing you access to an existing podcast directory which you can then favourite, rather than letting you interact with feeds directly, though if I remember rightly you can copy the appropriate rss information into supernova and have it play episodes for you.
lastly, when my lady tried her bard account on the supernova addon it wouldn't actually let you play the books on the pc, just search and then download them onto a compatible usb device.
So basically it seems that the entire media section is more a way of shortcutting use of other programs than a real substitute for the functionality of those programs, indeed as I said I still suspect its essentially just an attempt by Dolphin to shirk on their responsibilities, just the same way when I pointed out to them that Supernova would no longer let me use what mail client I wanted they said "Well we only support windows live mail or microsoft outlook"
I wonder how many people have complained to Dolphin that supernova doesn't support a given mediaplayer only to be told "well we only recommend using the media section of Supernova"
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)