Okay, i`m not pure FOSS user, but i hope one day I will be. This is what I use on my GNU/Linux desktop " Storm " and on my laptop " Desert " almost everyday.

Internet

• Gaim or pidgin now an open source IM software which supports MSN, ICQ, YAHOO, Jabber, Gadu-Gadu, and more protocols.. What i hate about it the lack of Video/Voice Support even once upon a time there was a good project called gaim-vv.
• Firefox very powerful internet browser, the most sweet thing about it that it do have tones of extensions, for example it have an IAX client so you have your phone embedded into your browser.
• Irssi an amazing IRC client which also has lots of plugins and themes, to be honest i'm keyboard / black screen fan, so irssi is amazing tool for me, at least I can control my music using it.
• ThunderBird for reading emails using POP or IMAP, also I did use sylpheed-claws before wich is fine not bad.
• Skype (proprietary) it's a shame that there is no alternative as good as skype under GNU/Linux, ekiga will be very good, but it needs some more time.

MultiMedia

• Mplayer I think it's the most used media player under *INX systems, supports VCD, DVD and all u need. * mpd a little bit fancy to have a music player daemon running, so you can control you music from any running terminal or even from any application that has a client to control mpd.
• mpg123 sometime I use to play some music too.
• Gimp for photo editing/creating also very nice tool, not as powerful as adobe photoshop but one day it will be.
• Gqview to open and view any kind of photos i have.

Office Stuff and text editor

• OpenOffice I'm not an office suite user I don't use it that much, but when I have too then I do use OpenOffice.
• Katoob a very light GTK writer which is created by Msameer, and it's nice tool.
• Xpdf a PDF reader , it's not the best one but i do like it's old gray look.
• VIM a consol based text editor which has also alot of highlight modes and alot of useful plugins.

I think that is all for now, but I hope soon i'll do updates on this page with other application.