Windows: With a touchscreen computer or tablet, you can use gestures to interact with apps. Just Gestures lets you perform customisable gestures with your mouse in Windows.
There are 32-bit and 64-bit editions of Just Gestures to choose from at the download page. Grab the version you need and get the application installed. Launch the program and use the wizard to select the "Toggle Button" -- the mouse button that will activate gestures.
There are a number of ready-made gestures built into the program, and you can see these in the main window. For example, there's a gesture for launching Notepad by drawing an N shape while holding down the toggle button. There are also gestures for common Windows actions like copying, pasting and manipulating application windows.
You can change these gestures to any shape you want. Right click any entry in the list of gestures and select Modify. On the Gesture tab, draw the gesture shape you'd like to use and click OK. You can also create completely new gestures. Click the Add New Gesture button, choose from one of the pre-defined actions or specify an app to launch with the gesture. Draw the new gesture, assign it a name, and click Next followed by Finish.
Just Gestures also supports the use of gestures to trigger keyboard shortcuts, as well as application-specific gestures. You can make the program as simple or as complicated as you want. It can be used for little more than starting apps, or you can spend time configuring more complex combinations of key presses.