Platforms I Know

I just wanted to note down which all platforms are there where applications/products are being developed.
Which of these are selling like hot cakes. Which of these I know and which I want to learn.

Platform where development is very active

• Windows
• Smart Devices
• Web Development
• Cloud Development
• Cross Platform suites

Platforms knowledge of which is selling like hot cakes

• Smart Devices
• Cloud

Platform of tommorow:

• Cloud
• Cross Platform Suites