This may exist, but I haven't found it...
I'm thinking that when I copy/paste a file from one location to another currently it only asks if I want to skip or overwrite.
A new item could be added to "Rename original file(s)." Ideally this would accept wildcards so that you could either rename the entire file or just append to the end of it.
For example if I was to copy Test.txt and overwrite Test.txt, I would like to have it automatically change it to Test.txt.6.15.2009.