I generally prefer informative textual System Tray (Task Bar / Notification Area) apps over less-informative graphical ones. However, due to limitations in the common graphics libraries, textual apps are extremely hard to find, so I have written a few of my own. All of these apps use the GtkTrayIcon library (provided in the gtktrayicon subdirectory). I use these with Trayer, but they should work with Gnome, KDE, Enlightenment, or any other window manager with support for the freedesktop.org System Tray Protocol Specification.
See the comments at the top of each app's script for setup and configuration.
Canonical source can be found at https://github.com/PaulSD/Tray_Apps.
Inspiration for these apps came from http://code.google.com/p/gtk-tray-utils/.
These programs are free software: you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
These programs are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with these programs. If not, see http://www.gnu.org/licenses/.