I want to choose between several OS's during startup. How can i manage this by using my bluetooth keyboard/Cellphone or at least my IR remote?
Disclaimer: I'm not an expert for GRUB and I'm using my general knowledge about PC hardware and software here.
As far as I know, GRUB is using BIOS to get input from the user. Thus, unless your PC (or other device you're running GRUB on) has support for Bluetooth/IR remotes in BIOS, there's no way you can do what you're asking for. Also, if you happen to have a wireless keyboard with host side wireless base, which is pluggable into a standard USB or PS/2 port, it might work (as long as BIOS sees such a keyboard as a normal wired keyboard connected to USB or PS/2 port).
Other alternative would be to modify GRUB (add support for Bluetooth/IR remotes/etc), but that's a story of a completely different complexity. :)