The one that's been around longest but the most limited is the ASE (Android Scripting Environment) http://google-opensource.blogspot.com/2009/06/introducing-an...
Using the ASE you can create some simple programs to do small tasks.
If you're looking to build a full app you're probably going to be looking at either working through Java, or if you're on Gingerbread you can use C++. Previous versions of Android allowed for C++ libraries being linked to your apps but had no way to access the APIs for creating graphical interfaces. That's now changed so I recommend you look into the SDK and NDK if you're really serious about building on Android. http://developer.android.com/sdk/ http://developer.android.com/sdk/ndk/
The only other option that I know about is that the Mono framework is being ported to android (.NET framework port). So if you know C# or any other .NET language you may be able to start there, although I think it's currently in closed beta. http://monodroid.net/