My friend Simon used to work on archive.org. So when I noticed that the complete Conet Project (recordings of shortwave numbers stations) was on archive.org in mp3 form, I emailed Simon about it. He then told me about Seism, a contributor who has uploaded recordings of numbers stations.
I searched archive.org for more shortwave audio. For something weird and noisy derived from shortwave recordings, try the Unproduct layered radio soundscapes (with low volume at first).
This archive.org query lists all audio files with "shortwave" in the description: shortwave AND mediatype:audio.
ShortWaveMusic is included in my links section. The author posts audio creations derived from multiple shortwave sources. [shortwavemusic hasn't been updated since January unfortunately!]
Here's a collection of shortwave recordings on another site. Visit Hugh's Awesome Shortwave Recordings and listen to many station IDs, jingles, and more in realaudio format. That page links to intervalsignals.net which is also worth visiting.