Today I took, and passed (!!!) the Extending CRM 3.0 certification exam (MB2-498). This was quite an accomplishment for me since I am not a developer (these days, but I used to be one heck of a programmer in the '80s! Maybe again...). I learned an awful lot working my way through the course. Granted I pretty much copied the code from the solutions to the exercises, but that still gave me great insight into what was going on.
One of the things I enjoyed learning about was Callouts (now called Plug-Ins in 4.0). These are extensions to the business logic in CRM (hang on). In the other courses and exam I've taken, Callouts were mentioned but never explained, at least not HOW to do them. But all the CRM Gurus (the other CRM MVPs and others) casually mention them with great familiarity. Well, the Extending course explained, finally, what they are and how to use them. Basically Callouts are configured in the Callout.config.xml file and can be configured to run before an event, like creating a new Account or other record, or after. These are called Pre and Post callouts.
The course also covered how to write web pages to access CRM data, use of web services to process and update CRM data, and a whole bunch of other stuff. All in all it was great to finally work my way through the material. You can find a bit more info on the test here. Even if you are not a developer, going through this course will give you a greater understanding of the capabilities of Microsoft Dynamics CRM.