My personal preference is jEdit [www.jedit.org
]. It's a very mature editor (just released version 4.2), with a TON of features, and a ton of plugins to add even more features. The other nice thing -- since it is java based, you know that no matter what system you are working on, you can be using jEdit (so you don't have to learn/customize 2 different editors for 2 different environments).
Here is a list of features from the website:
# Combines the best functionality of Unix, Windows and MacOS text editors.
# Runs on any operating system with a Java 2 version 1.3 or higher virtual machine - this includes MacOS X, OS/2, Unix, VMS and Windows.
# Efficient keyboard shortcuts for everything
# Comprehensive online help
# Unlimited undo/redo
# Copy and paste with an unlimited number of clipboards (known as "registers")
# Register contents are saved across editing sessions (4.2)
# "Kill ring" automatically remembers previously deleted text (4.2)
# Rich set of keyboard commands for manipulating entire words, lines and paragraphs at a time
# "Markers" for remembering positions in files to return to later
# Marker locations are saved across editing sessions
# Any number of editor windows may be open, each window may be split into several areas, each area can view a different file. Alternatively, different locations in one file can be viewed in more than one area
# Multiple open windows and split windows are remembered between editing sessions (4.2)
# Rectangular selection
# Multiple selection (sometimes known as "discontinuous" or "additive" selection) for manipulating several chunks of text at once
# Word wrap
And that really just scratches the surface.
There is a ton of nifty plugins for Java development, but I even do my non-java programming in it.
EDIT: You can have a transparent/tinted background with the use of the "background" plugin. Another essential plugin is FTP. Open/Save files seemlessly over FTP or sFTP.