Nude - removes your window dressings.
Nude is a simple python/gtk app which runs in the background and strips all but a very small border from every window you open. Primarily designed to work with the Metacity/Mutter/Muffin family of WMs but will work with most WMs.
I've tried multiple times to use a tiling window manager but they tend to destroy apps which need to manage their own window placement (gimp, my custom vim extensions etc).
Metacity/Muffin/Mutter have some really nice shortcuts for moving windows (ALT-mouse) and snapping them together (SHIFT-ALT-mouse) so you can replicate tiling fairly quickly when you need it, all that is left is to remove those annoying window decorations.
Nude is a single python file, it requires python-gtk and python-wnck which you can probably manage installing yourself with apt or something. Then simply run ./nude.py&, perhaps from your ~/.xsession, add it to startup applications by running gnome-session-properties or find some other way to run it on startup :)