Radio disc jockeys once were kings. They will be again, and we'll all be royalty if PartyDJ ($30 for non-commercial version, $50 for commercial; 15-day free trial for both) has anything to say about it. I've reviewed a couple of organizers and playlist generators that stream music, but PartyDJ is the first that didn't require tech-savvy mucking about with Icecast or other tools to broadcast music across the Internet.
With PartyDJ you simply select RadioDJ from the Tools menu and a dialog pops up with all the pertinent information: the mms address (mms://67.160.238.xxx:8000) on which the player will broadcast, firewall settings, router settings (you must forward port 8000 to your local IP address, e.g. 192.168.1.100). It doesn't tell you how to apply the firewall/router settings, but a few minutes studying your router manual should suffice for that.
Once your firewall/router is set up, it's a snap to begin broadcasting. Simply play the PartyDJ playlist you've created and press the start button in the RadioDJ dialog. That's it. Surf to the mms address (this will probably open up your default Internet Radio player such as Windows Media Player) and if you've done everything correctly, you'll hear the music playing. Trust me, it's not that hard--and even in the personal-use version, you can have up to 5 users listening at a time.
Internet broadcasting is PartyDJ's most salient feature, but there are numerous others: ripping, burning, organizing, tag editing info, and lyric grabbing, etc. The interface is a bit plain-jane, but it's also easy to use and the reliance upon text rather than forcing you to memorize yet another set of icons makes it easy to learn. The program requires Microsoft .NET Framework and is dependent upon Windows Media Player for streaming, ripping, and viewing movies.
PartyDJ comes in $30 non-commercial and $50 commercial versions, the former supporting 5 users and the latter 50. The commercial version also adds the ability to schedule commercials. If you don't mind being Microsoft-dependent, PartyDJ is a winner. It's surely worth your download bandwidth if you have any interest in DJ'ing. At the very least, it'll give you a handle on how to configure other broadcast software.