Hey, a subject I can Chime in on
IRC games are great.
1. <B>Ease of Finding Players:</B> People I've met on line have always had contacts that they know are good gamers. Its not difficult to find the cream of the crop gamers.
2. <B>Dice bots are cool:</B> The one I use (and the DMs of other games I play) -
http://www.geocities.com/Area51/Shadowlands/2309/dnd_dice.html - have quick, easy rules. As a bonus ... the name can be changed to assume the persona of an NPC so that the DM can still keep his nick the same.
3. <B>Flexible hours:</B> A game can be run when ever you like.
4. <B>Cut/Paste:</B> As mentioned above, preparing an adventure in a text editor allows for easy posts.
5. <B>Online Aids:</B> Visit geocities or some other site and badaboom, you can create a Primer for what ever adventure you are running, a blank map, campaign docs, pictures of NPCs, etc.
6. <B>Availibility</B>IRC has many servers all over the place. Recently, a couple of my games went over to Psionics.net.
Drawbacks
1. <B>Users:</B> IRC has massive numbers of users. If you don't take the proper precautions when creating a room, every Tom, Dick, and Harry can walk right in ... sometimes disrupting play.
2. <B>It's online:</B> IRC servers do crash. Its easy to switch servers, but when you do, all room settings you had before are lost.
3. <B>Distractions:</B> Computers are now very fast and allow for multitasking. Some players are easily distracted by out of game conversations, browsing the Internet, or playing a game.
4. <B>IRC Itself:</B> There are a lot of finer points in the IRC that can be obscure for new users; however, there are many comprehensive web-aids which can help users solve their problems.