Conversation Manager 

Conversation Manager was written to help sort out the mess of text that one can accumulate when talking in raid, guild, a couple channels, and getting 5 whispers at a time.

The main window is pretty much self explanatory. Possible 'conversations' you can have are listed on the left side: Party chat, raid chat, guild chat, officer chat, channels, and whispers from other players. Clicking on one of them will give you your conversation history with them in the frame on the right side. This is an EditBox (though editing is not permitted), so you can select and copy from it, though the downside is you are unable to click on links inside it. A separate links panel is available on the side for clickable links. If a channel is selected, a list of players will be shown in the links panel instead.

The history is saved between sessions, to help against missed chat say if you AFK and timeout, or get disconnected. Crashes obviously won't be protected against though since variables won't get saved on a crash. The history is also kept on a per-realm basis, so one can simply continue conversation with someone when you've switched characters.

Whenever a message is received, either in guild chat, channel, or a whisper, that item will blink (if that option is enabled) to show you a message has arrived. By default, blinking is only enabled for channels and whispers.

/converse help will give a list of options:

/converse hide/show - hide or show window
/converse lock/unlock - lock or unlock window for dragging
/converse reset - reset window position, in case dragged off screen
/converse fontsize # - change font size in history window
/converse maxlines # - change maximum number of lines kept in history
/converse clearall - clear ALL history for ALL conversations
/converse clearchat - clear group/guild chat history
/converse clearchan - clear history for channels
/converse clearmsg - clear history for whispers
/converse clearrand - clear history for non-friend whispers only
/converse blink - toggle blinking for party/raid/bg/guild/officer chat
/converse chanblink - toggle blinking for channels
/converse msgblink - toggle blinking for whispers
/converse sync/nosync - set whether your chat entry box follows whoever you have selected in the main window at the time
/converse date/nodate - enable/disable datestamping
/converse altchat/noaltchat - enable/disable alternate IM-style editbox. Note that this editbox is for chat text only, will not deal with slash commands, and you cannot shift-click links into it.
/converse gemfilter/nogemfilter - enable/disable GEM channel filter
/chatall - refresh list of players for all channels

At the top of the main window are checkboxes which allow you to ignore certain channels/etc. so that Conversation Manager does not keep a history for them. This allows you to, for example, ignore General chat, or other addon communication channels, or hide the Guild/Officer spots if you are unguilded or not an officer.

Known quirks:

Every now and then when switching to a new item and the wall of text is updated, it will fail to scroll to the very bottom. Reselecting usually will cause it to update properly... but not always

I recommend not setting maxlines too high if you have a slower system, as can will incur lag for every new line received when a history starts getting big when you have the links panel open. The default is 256, double the 128 of the usual chat history box. 1024 lines seemed to work okay on my already addon-bloated older computer (Athlon64 3200).

Thanks to Mikk for his ChatThrottleLib