I want to leave Gnome and install awesome on debian squeeze or wheezy, but I really can't work without gedit. Is there any text editor like gedit capable of editing columns, highlighting nearly any language, and building texfiles straight from the editor? The wealth of features is important to me because I want to use it as a central "IDE". I've tried Eclipse, but didn't care for it.
I agree with Marco that sticking with gedit makes sense. After all you say that you cannot work without gedit.
However if you are prepared to spend some time learning a new editor and are curious of how an editor can help you even more than most editors I recommend Vim or Emacs as it is possible to be very productive in them, they are very capable and configurable, has helpful communities and they can be used with few dependencies (they may even be pre-installed on many *nix systems). I used to do my work in gedit but two years ago I started to learn Emacs and I now do most of my work in it and I am very happy with it. The problem with Vim and Emacs is that it takes some time to learn them as they are quite unlike many other editors. Initially it may be a good idea to use an editor you know well in parallel to Vim or Emacs so that you can focus on your work when you need to. If you want encouragement and tips for learning Emacs see the section "Learning" in this answer to a question about learning Emacs.
To answer you question (instead of saying to stay with gedit or recommending a wholly different editor) an alternative to gedit that has fewer dependencies and the features you ask is Geany. It is presented as
a text editor using the GTK2 toolkit with basic features of an integrated development environment. It was developed to provide a small and fast IDE, which has only a few dependencies from other packages.
When checking out its dependencies in Ubuntu it indded has fewer dependencies than gedit. Also it seems to have the other features you mentioned: it can edit columns, it can syntax highlighting many languages and it has an interface for building. Geany also has other features in common with gedit. For example, it has a snippet manager and a plugin system.