I don't know if this has been posted before but I just got done reading through the turbo tech pages and it was rather interesting. I thought it would be a good thing for people that don't know much about turbos or want to learn about compressor maps. I don't know if we can post a link to it on the main page or something. If not, at least it'll still be in the search!

http://www.turbobygarrett.com/turbobygarrett/tech_center/tech_center.html