Snork --
First... let me be totally clear that you gain NOTHING by fibbing about your medical history to get certified. Answering yes to any question on the medical history form is not saying you can't dive -- just that you need to talk it over with a doctor. Those questions are not being asked to protect your instructor... they're there to protect you. So please don't fib on your medical history forms.
That said... I've posted several pages of information on my web site related to this question. The first page is the medical history questionair that SSI uses to screen would be divers. The bottom line is that if you answer yes to any question on that form, then you should have a sit down with your doctor and get a medical waiver from him/her. Here's the medical history questionair...
http://www.learn-scuba.com/documents/MedicalHistory.jpg
Okay... what happens if you answer yes to any of those questions? Well, then you should print these next four pages and take them to your doctor. They are the medical guidelines the doctor needs to make a determination whether or not it is safe for you to dive and what precautions you should take if you do dive. Besides letting your doctor look at this information, you should also have the doctor talk to a dive physician and DAN. The DAN phone number is on these pages. So, if you answered yes to any quetsion on the medical history, print these four pages off...
http://www.learn-scuba.com/documents/MedicalGuidelines_pg1.jpg
http://www.learn-scuba.com/documents/MedicalGuidelines_pg2.jpg
http://www.learn-scuba.com/documents/MedicalGuidelines_pg3.jpg
http://www.learn-scuba.com/documents/MedicalGuidelines_pg4.jpg
Lastly, you would want to have your doctor sign a medical waiver for you if he/she feels it is okay for you to dive. This is the form used by SSI and I provide it here only as an example. Each agency has it's own guidelines and medical waiver forms, so this is only useful if you plan on training with SSI. Otherwise, you should get medical waivers from the dive shop you're going to train with. But, in any case, here's what the waiver looks like.
http://www.learn-scuba.com/documents/MedicalRelease.jpg
Note: If you do need a medical waiver, have your doctor sign three of them... one you take to your dive shop, one you carry with you any time you are going diving and a spare you keep at home for safe keeping. You should get a new set of waivers signed off every year when you get your annual physical done.
Best of luck to you!
Edited to fix URLs for medical info