It features syntax highlighting, syntax validation, MDI notebook based interface, quick CSS properties and values insertion, auto-completion and dialog-based insertion of CSS complex values. Being a CSS editor, it's not limited to this language. cssed
"Glade is a RAD tool for the GTK+ toolkit. By using libglade, Glade XML files can be used in languages including C, C++, Java, Perl, Python, C#, Pike, Ruby, Haskell, Objective Caml and Scheme. Adding support for other languages is easy too."