Yes, Alt-Tab is weird.
If you do:
Code:
C:\>adb shell input keyevent 187
You'll get the popup APP_SWITCH which stays until you select.
You could generate this by remapping a key in keylayout.
There are a few things (Contacts, Calculator, Call) that have their own keys. There is no general provision for FB, Twitter, Maps, whatever. You could do something with intents.