Being in Australia, I do a lot of online chatting with the rest of the world which is often handy to refer back to. I know a lot of other people here often work across countries, so I thought this might be useful for some of you too.
This program basically indexes your iChat logs. You can browse, search and export them to HTML. Oh, and it's open source (BSD-style license).
The project is at http://chatsearch.sf.net/ , but I have hacked the source and built an app that has (IMHO) a transcript layout that makes it much easier to browse long chats. You can find my modifed version at:
http://mark.aufflick.com/files/file?file_id=1388