Homebrew PCBs

Hi Group,

Are there any guidelines as to the relationship between trace 
thickness (width, I guess) and the current it can handle?

I know that copper clad boards come in different weights of copper, so 
I suspect that with a higher weight, you can get more current in a 
narrower trace.  

In an industry loaded with specs and datasheets, I am hoping there is 
some sort of guide somewhere on this.

TIA

Chris