the flash player doesn't let you change the flashvar settings after the page has loaded so it'd be as simple as adding a link on the page somewhere for /opentape/?shuffle=true
I presume shuffle shouldn't be the default, and therefore that you'd prefer the first, but there might be some crazy shuffle-loving opentapers out there. (Above code not tested, no warranty expressed or implied, use at your own risk, ymmv, omgwtfpwnies)
I ain't crazy, but having a link or button to switch/reload the page into a shuffle mode, would be great!
I also don't see why the track listing displayed would have to change, just provide a shuffle button that is visually engaged or not (depressed, or not), and if engaged, the track advance would jump around at random, instead of sequentially. Ideally, you could start the list from the top, let it play down in order for a few songs, decide you want to shuffle now, click the button, and the next advance will jump to a random track.
Realize also, that we're getting away from the simplicity of design here, and more importantly, the history and ethos of the actual, linear mag' tape "mix tape", in which the creator determines the order of the tracks, and orders them a certain way on purpose. So if this feature is offered, it should also be something only the admin login can offer/engage, or not offer (to display the shuffle button, or not.) Ol' skewl says, "mixtapes don't shuffle." That's the way it was, by technical and artistic design. Mixtapes came well before CD's and digital files and players, and linear tape on a reel couldn't really be shuffled, at all.
We're trying to intermingle the Muxtape simplicity and mixtape tradition, along with all the features offered in every other digital audio player out there, from Winamp to iTunes. Heck, there was already some kind of little proprietary PHP code package (product) you could drop into your own site, that would provide an MP3 player "widget", which would either play in order, or shuffle, etc. The trial would allow just a few songs in the list, but the paid version was unrestricted. Had a short name, one word, I played with it and it worked flawlessly. This was like 18 months or two years ago. (Ahhh, thank you Google - "Wimpy" http://www.wimpyplayer.com )
And, here's this: http://musicplayer.sourceforge.net/ but it looks like development stopped some time ago, though I've seen this widget on all kinds of pages, everywhere, to this day.
I agree with the desire for simplicity, and screw the person who says that more bells, whistles, and chrome help the project. On the other hand, FOSS exists to scratch itches- if someone wants a more featureful OpenTape, they can fork it. I agree OpenTape will probably see more success if it stays simple and easy to install- but I think that adding some features isn't a sin, if they do fit in with that mixtape ethos. Which features do that is up to the project maintainer, though.