I got a really strange problem today when I tried to get MADDE working. When I am in mad-developer and try to load g_ether it first seems to work OK, but when I push in the USB cabel it says "Doesn't load, not enough current". And I think this is the problem wich make me not find maemo in the options/qt4. What could I have missed? I tried to have the cabel in the device when loading g_ether and I have tried to use offline mode (the gprs problem I read about).

PS. I did everything as they did in the wiki

No. I can see that if my N900 is not even connected.
You have to follow the steps described in the Qt Creator integration page of the wiki to make it appear.

I am doing that, but I think I found the problem hopefully. In the wiki it says "Install latest QtCreator on your PC
You cannot use the latest official QtCreator for this." And I did just read the first line...

When I try to rebuild the qmake I get the debug error "The Qt Version has no toolchain."

You do need one of the latest versions of the upcoming version 2.0. The alpha has been released a couple of weeks ago, but you can also go for a recent snapshot.
Those can be found here: ftp://ftp.qt.nokia.com/qtcreator/snapshots/

After adding the Qt version, does it recognize it correctly as a Maemo version? Switching to the Maemo target should only display one Toolchain then.