A common request has been 'smart' playlists. While I can't provide the full-feature (every tag is available) smart playlists of iTunes, I did write an application that will create stations and allow you to re-visit and re-shuffle the stations on demand.
Each Station is a public/shared playlist (with a specific JSON syntax in its comment), with a list of generators, like "top songs", "album", "random songs", each based on the core fetching methods from the Subsonic API. Any number of generators can be added to a station*, and generators can be limited on how many songs it contributes to the shuffle.
Visit
http://subfireplayer.net/radio/ to try it, or go to
http://subfireplayer.net/subfire-radio/ to read more. Like SubFire, the radio generator app does not use a proxy or store your data on any cloud server other than your own Subsonic instance or as local storage on your browser. HTTPS *should* work (even when you have a cert exception for an unsigned cert in your browser), but I can not test it.
* or at least, I haven't found a length limit on the comment of a playlist yet.
Feedback can be left here, or in the support page specified on the documentation page.
Note: It uses some newer browser standards (fetch and promises), which means it currently only works on Opera, Firefox, and Chrome. I am working on adding some polyfills for IE and Safari.