well i got just started on my own vl pingutop just recently....so i'll write about the few apps that i use for day-to-day stuff.
JuK for songs
VLC n Xine for videos...majorly VLC
openoffice impress to read lecture slides
firefox for browsing
armagetron advanced...but i like savin some flash games on to disk n play em offline
vim....to do occassional configuration messups of scripts in etc., wonder at the colors of c codes that i take inspiration from n read RFC's
for editing code myself, i prefer kwrite
...to the person sayin latex for typesetting. did you build latex from source or do you have a binary package...the latex site has quite an attitude problem...hopin it comes pre-installed with your distro or with some random tex package...i installed tetex but kile can't find latex.
well there are a lot of other small applets that i use n what else... oh
su .... its an app ain't it. i use it quite a lot...like ubuntu guys would be using sudo all the time
vcpufreq: i like my cpu runnin cooler
mcedit...the safer way to edit when u dont know that typin 3dworld in escape mode of vim is dangerous for existence of the characters on screen.
slapt-get .... favorite way to install...although i know the binary package is not always optimized for my architecture.