ProScan is great, but of course it requires listeners to download that client, as well, which limits use a bit.
The assorted 'standard' audio streamer programs like icecast/simplecast are more common, and pretty much anyone can 'receive' them with the software they have, but they tend to require more 'setup' knowledge from the sender.
There's also Teamspeak 2.0, which is used for quite a few scanner feeds to central servers, and is quite good at it. Again, users must download the free teamspeak client. This is a handy method to use for 'situational' feeds, where the central server adds short term feeds from its users who happen to be in the area of a current major incident, as well as more long term feeds.