Applications are now becoming fairly common where you're able to 'stream' your own music from your computer at home. These have rather escaped the watchful gaze of the RIAA so far, but I wonder how long that'll last. In practice there's no real big technical distinction between streaming and downloading, so every song streamed represents a new generated 'instance' of that song. (In the sense that it's just 1's and 0's in memory space, whether that's in a temp file or a permanent one) And moreover lots of the software I've seen (Firefly for one thing) allows the client to 'properly' download the file anyway. Given that we're not supposed to be making extra copies of even music that's been paid for, this represents copyright infringement, surely.
How about if you give your password to another user, who can then stream your music from your server? I know at least one application that offers and encourages this as a proper feature; Firefly even allows you to host a flash web-based music player as a webpage. How about some kind of clause that people should only be able to access their own music? Or can other users get in, but only listen to the things that they too own?
One argument I see on here a lot is that 'streaming' off myspace, last.fm, etc, is fine, because it can't be saved and used for other purposes: ie. with iPods. This one's falling apart though: last.fm and other similar sites are now available via mobile data devices (I can get unlimited data usage for a fiver a month nowadays). It's not amazing yet (in terms of speed and coverage), but when this kind of thing picks up people will be able to listen to new music 24/7 without ever having to spend a thing.
Suggestions of a general tax/levy on internet usage seem to be the only practical way forward I can see in actually extracting some money out of these services.