I'm always seeing babble about "GCSEs." Can I take one to see how I do? Any discussion seems as though a person obtained a PS3 on its first day of release.

There is probably an American centre registered to allow you to sit a GCSE, or IGCSE, but the use of it as a qualification to you, and the fees incurred probably outweigh the benefits.

 

You could always sit a past paper and grade it yourself to see what equivelant level you are at?

Depending on the exam board, you can find a lot of past papers online as pdfs on the respective exam board websites. Why not try one? The major exam boards are AQA, Edexcel and OCR. You should be able to find the websites pretty easily by searching google, or whatever engine you prefer. Also I think you'll find them a doddle;)