If you have access to a remote computer through SSH, but you're not very comfortable with the command line or for any other reason, you can mount a folder or the whole filesystem through SSH. This can be done in 2 ways:
Wasp, one of the Ubuntu Lucid proposed themes has been updated to version 0.8.
The new version does not require the Stylish addon for Firefox and also, there are not multiple versions anymore, just an editor you can use to create your own Wasp suited for your taste:
The first 3 XSplash themes (screens) are part of the Fusion-GX-v00 pack and can be downloaded from the same location - download link after the third XSplash.
Update: it also works on KDE and LXDE
Renamer is a small python script for batch renaming files in nautilus, which comes with a GUI.
After we've seen a Chrome-like theme for Gnome, now it's time for a Wave GTK theme which is inspired by the new Google Wave interface and comes with two metacity themes: default and rounded.
You can set the Gnome panel transparency through it's settings but:
1. That's not true transparency.
I used some Compiz settings and Namebar to hide the Windows titlebars and display the window title and buttons on the Gnome panel.
Based on the Ubuntu Sun concept and New Wave, Narfss has created a Gnome theme for which the titlebar (Metacity only) changes automatically depending on the time of day (dawn, noon, evening and night).
Some Nice and Polished Gnome Panel Backgrounds you can use in any Ubuntu version.
3. Karmic X
You already know PackoXsplash HD (we wrote about it a few days ago) which is my favourite Xsplash, but I guess not everybody likes the same things, so here are some other nice Xplash Themes to use with your new Ubuntu Karmic Koala 9.10.
Shotwell is a relatively new open source photo organizer designed for the GNOME desktop environment. It's purpose is to allow you to easily organize your digital camera photos (basic editing included).
Seahorse is a Gnome front end for GnuPG - the Gnu Privacy Guard program. It is a tool for secure communications and data storage. Data encryption and digital signature creation can easily be performed through a GUI and Key Management operations can easily be carried out through an intuitive interface.