I thought I would challenge myself to write a mobile app. I personally have an iPhone, but didn't want to invest in a MAC to develop an application and then having it rejected by apple. So I opted for and android based app. I had a look around at the subnet calculator market and though I could do a better job. So here is my effort https://market.android.com/details?id=net.networkingguru.SubnetMaster All the coding was done over a few weekends. There are still lot of refining required, but I feel it is ready for a beta release.