I'd like to add the following:
IRC client
KVIrc:
http://www.kvirc.net/ (one of the best free IRC clients I've ever used)
Audio player
XMPlay:
http://www.un4seen.com/
XMPlay is more for people who want a very small non-install audio player. It also contains the best tracker playing engine, BASSMOD. Supports MP3/2/1, Wave, Ogg Vorbis, MOD, S3M, IT, XM, MO3, UMX. One very good thing about it is it supports Winamp input and DSP plugins.