intellectualheaven.com
SniffIM v0.7 -- SniffIM is a Yahoo and MSN Instant Message Sniffer. It can sniff Yahoo and MSN IM conversations going on in a network. It works on Windows 2000, XP and 2003. Latest version supports minimizing to system tray, displaying timestamp and IP addresses in captured messages.
YahDecode v1.1 -- Yahoo Message Archive Decoder now supports decryption of saved yahoo password, decoding of multiple archives and ability to search in archives by exporting all the decoded conversations to RTF file.
+ some other awesome tools on that site as well.