An IDE which supports Android development is Processing for Android: http://wiki.processing.org/w/Android. Processing is its own language but it's easy to learn. Processing for Android requires the JDK and Android SDK to be installed but runs on its own. It runs on Linux, Mac OSX and Windows (on a side note: one can develop a desktop app in Processing and then compile it to target any of these operating systems). Its development is ongoing but it works. It's especially good for quickly sketching up an idea and running it on your Android phone (even if you plan to develop it further in another IDE).
There is an active support forum here: http://forum.processing.org/android-processing.
