Go to your application floder. It must be in the workspace of eclipse. Inside application, there is bin folder. The apk is generated inside bin/ folder.
In the phone, pre installed apks are kept in system/app folder and installed applications are kept in data/app folder. Your phone should be rooted to access this folder.
But you can write small code to see what apks are present in this folder:
File apkDir = new File("/data/app");
String[] apkFiles = apkDir.list();
for (int i = 0 ; i < files.length ; i++ ) {
Log.d(TAG, "File: "+files[i]);
}
Hope this helps