KDE has a neat little feature called "Input Actions". Here you can define certain triggers to do certain things, such as keyboard inputs, DCOP calls or just running executables.
Combine that with a Macbook remote which has some keys assigned to it via xmodmap and two clicks in the control center can change from one group of actions for the available keys to the next.
See here for how to assign keys with xmodmap. In my case I gave the keycodes values such as F13,F14,F15 to not have conflicts with other applications.
I now have a group for amarok to use the remote for browsing through my music collection and a group of actions to control
Powerpoint OpenOffice Impress when giving a presentation.
This is probably also doable through lirc but the KDE daemon for that didn't seem to recognize anything even when I pointed him to the right event interface. It worked fine in irexec but the integration through the KDE daemon was my only interest here to have the already scripted actions available but Input Actions proved to be far more flexible. (I also use them for the FN keys on the internal keyboard for brightness, mute, volume.)