While you could wake up your PC from a mobile directly, having a dedicated server capable of doing so is the best solution. The reason is simple. You can hook up as many devices as you wish with a single endpoint. This is why Raspberry Pi is perfect for this.
You can get rid of all barcode enabled discount cards now!
Launch apps and websites from the mobile!
Use NavBar to bring out your personal ClipBoard Manager when you need it most.
Create a clipboard manager with AutoTools WebScreens and Tasker
Update the global variable each time your server variable will change so you could always send and receive the data from the correct IP
Get international with Tasker and this Whatsapp profile
Not the easiest project to explain.
Fancy some training on .json, subroutines, arrays and loops?
Going out and about? Make sure someone knows where you are.