Here is another tutorial from Francis Preve over at beatportal. He has a great writing style that is easy to follow and makes quite a lot of sense.

Francis Preve has posted a great tutorial on compression over at Beat Portal. It's a great tutorial that is easy to follow and understand. If you're interested in production this would be recommended reading.

The guys over at audiotuts have a great tutorial for processing vocals in logic studio. They cover removing hiss, compression, eq'ing, reverb, delay and pitch correction. Very good tutorial.

The guys over at AudioTuts have a great tutorial aimed at using Apple's GarageBand to create professional podcasts.