I dont think it's practical to rely on memory for passwords anymore. If it's a site you really couldnt give a damn about, then sure, as long as you're okay with whatever information you submit being potentially linked to that password and to any other information.
I just use a text file on my computers desktop and a usb thumb drive. I don't note what the password is for. So my Amazon password is something like dkwjRw#4camzR4%7hjfgdelsdshWE