There is also application that looks interesting with or without the hardware microphone called EZ Voice.
Maybe the biggest thing is that you can without paying any money is to load a track and sing on top. Otherwise there is as you can see in the image above eight effects available all related to enhance voice / vocals. Each one of the effects cost 0.89€ / 1.21 $ except the reverb that comes for free if you register.
To be honest have not tried the application much but it seems so far to be solid and can be useful for anyone that do want to keep all the production inside Android devices.
The microphone can be a good buy to as it is not to expensive and it seems that it have similarities with the iRIG Microphone that I have so it is probably of good build and can stand some abuse, it is also a bit cheaper and can see some instruments keeping in the same frequencies as a voice being treated nicely sonically.
Play Store link: