Besides On the Run and the first two Horizon adventures, are there any SR4 adventures that have to do with musicians or the music industry? I'm also including the various plot-point books as well.

If you include 1st and 2nd edition adventures, there are a lot. Mercurial is a classic, of course, but there are also Dark Angel, One Stage Before and Total Eclipse, off the top of my head. I think those are all the adventure books, but there may be more plot hooks in other publications, as well.

Wish I had those adventures as I have not been in any of those particular ones.

I'm not really interested in non-4E adventures for a number of reasons. (Mostly related to time and plot.) Thanks for the idea, though.

I cannot think of any others (that you have not named) for 4th Edition. Though there MAY be some Missions that deal with that particular subject. *shrug*

even though the ones listed as 1st ed runs, they can easily be converted to 4th ed if nothing else they give great ideas

They're really not that hard to convert, honestly. I recently did a conversion of Dark Angel for my group (which, when our laptop died, I lost all of my conversion notes. Sigh.) just using the official conversion guidelines.

But no, beyond what you've posted, there hasn't been anything else for 4e.