Markers in Logic

Here's a little video via audiotuts showing how to set up Markers within Logic.

Logic Pro: Markers from Elizabeth A. on Vimeo.

Creating custom EXS instrument

audiotuts has a nice little tutorial on creating your own cutsom instrument in Logic's EXS sampler.
It's only basic in that it covers loading a single sample, mapping it across the entire key range and adjusting it's loop points, but it's a good starting point if you want to start making your own instruments.

Comping in Logic

something/anything have posted a video on their blog highlighting how to easily create composite tracks from multiple takes.
This method would prove extremely useful when recording dialogue within films, amongst other things.