When you install Ubuntu 8.04 (hardy) desktop, you get a lot of packages installed by default. Most users will never use many of these packages, so you end up with a lot of unnecessary packages. Most of these packages are harmless and only waste disk space when not used.
However, some packages can actually affect the system in a negative way, such as draining resources (other then disk space), and you should consider removing them if you not actively use them.
To remove some of these packages, you also need to remove these metapackages:
ubuntu-desktop ubuntu-standard ubuntu-minimal
Tracker indexes your files in the background. This can slow down your computer considerably.
libtracker-gtk0 tracker tracker-search-tool libdeskbar-tracker
Locate is another tool for indexing your files. It makes not much sense to have it in parallel with tracker.
Some multicast DNS stuff. Contains a network daemon, and good security common sense tell you to remove all network daemons you don’t actually use.
avahi-autoipd avahi-daemon libavahi-core5 libnss-mdns
Quite useless if your computer doesn’t have Bluetooth.
bluez-audio bluez-cups bluez-gnome bluez-utils
Can be good to have on a laptop with wireless networking. But makes no sense if you have a permanent wired network connection (or no network connection at all).
network-manager network-manager-gnome libnm-glib0 libnm-util0
Display a pretty image during boot, hiding a lot of possibly interesting messages. Does not work with some display adapters.
usplash usplash-theme-ubuntu libusplash0
A groupware suite, contains a daemon (evolution-alarm-notify).
evolution evolution-common evolution-exchange evolution-plugins evolution-webcal contact-lookup-applet libexchange-storage1.2-3
A text editor that some people finds very hard to use. Used by default by some commands such as
visudo, so you might accidentally end up in a awkward text editor you don’t even know how to exit.