On EFNet there are usenet communities that exist in channels such as #alt.binaries.multimedia, #alt.binaries.tvseries, #alt.binaries.games.xbox360 etc.
They have IRC bots running so you can add a request, if someone in the IRC channel has what you want then they can fill it. If they choose to mark it as filling they will then post it to the relevant usenet group (for example #alt.binaries.games.xbox360 users would post to alt.binaries.games.xbox360) and mark it as filled when it's posted.
Usually the commands are as follows:
-addreq [full/part] [filecount] [release name]
e.g -addreq full 95 The.Longshots.DVDR-ALLiANCE
The bot then announces that the request has been added to the database and assigns it a request number (e.g #4562).
If a user has it and wants to post it then they can type a filling command:
-filling [req number]
e.g -filling 4562
Now the bot announces that it is posting/filling. Once the person filling it has finished, they type the filled command:
-filled [req number]
e.g -filled 4562
The bot announces it's filled and then people can grab it. Most channels require you to use a specific posting header, normally containing the channel name and network (such as #altbin@efnet). Every time you fill something the bot gives you points, usually after reaching a certain amount of points you receive +v (voice status) and the ability to request/fill stuff anonymously by sending the commands straight to the bot (instead of typing them in the IRC channel). Some channels have slightly different commands/rules, so this might not be 100% accurate.